01 Chevy Venture Cooling Fans & AC Not Working

12-27-2016, 01:25 PM
(Update: The problem described here has turned out to be a leak in the condenser on the bottom, passenger side where the attachment bracket is. Links to pictures and descriptions below. It's a large leak which in this case caused the AC to go from nice and cold to warm air in probably just a day or so. The loss of refrigerant and low pressure causes the compressor clutch to stop engaging. The fans also do not turn on as they normally do when the ac system reaches a certain pressure. The leak is easily noticed by simply looking at the bottom corner passenger side of the condenser, at the front of the car in front of the radiator. You can see a very large oil stain on the condenser. )

2001 Chevy Venture

Does anyone out there have any further insight on how to fix this ?

Problem: Cooling fans & AC compressor not turning when AC is on full blast, & there's no cold air. Though cooling fans do at least turn on and cool properly when temp gauge reaches normal range.

1. first noticed a problem when temp gauge was running higher than usual. Found that passenger side radiator fan was not turning on, even with AC cranked. Found there was 14 volts at the fan connector. I replaced the fan motor. The fans then worked and were running properly. They ran when the AC was turned on and when the temp gauge reached the normal range to cool the engine they turned on. So it looked like all was good. But I had noticed while replacing the fan motor that the 4 pin connector to the 2 fans was burned on the side of the fan which had failed.

3. After a few days of driving i then noticed the AC is not blowing cold. Fuses and relays all looked good. I noticed the ac compressor was not turning. There was very low voltage at the connector. (Though I could not properly seat the multimeter probes into the connector as they were too big, so I'm not 100% certain about the reading)

4. I also notice that the cooling fans are not turning on either when the AC is on. They were running with AC on after I had installed the fan motor, at least for some time. And again, they fortunately do turn on when the temp gauge reaches normal range.

I believe it could be a bad ground connection between the compressor and cooling fans. The AC button inside the vehicle normally powers up the cooling fans and engages the AC compressor clutch. Looking at a wiring diagram I have attached here both the cooling fans and ac compressor clutch both have a black wire with a connection that says "S105, ENGINE HARN 4CM FROM ENGINE FAN WIRING HARN BREAKOUT". I am assuming this has something to do with the connection that powers them both when you press the AC button. Apparently there is short in this connection it seems.

Also, an ongoing issue for a couple years which could be related has been with code P0128. What happens every few thousand miles is the check engine light will come on & at the same time the temp gauge stays flat, and the cooling fans will run continuously. I found that by either removing & replacing the fan relays, or by clearing the code, the problem temporarily resolves and all goes back to normal for a few thousand more miles.

Presently I have codes P0128 as well as
P0141 - (HO2S-12 Bank 1 sensor 2) / Heater circuit malfunction
P0440 - EVAP System No Flow During Purge

The P0141 and P0440 are codes which I've never had before, but they don't seem related to this issue. P0141 (O2 sensor related), P0440 (gas cap, fuel related)

12-27-2016, 03:49 PM
2001 U-vans are patterened off of GM W-cars- which in their logic, the cooling fans wait until 175 psi head pressure to turn on the cooling fans upon a/c request. So if you have no compressor running- (due to loss of refrigerant and refrigerant pressure) then your fan(s) will not come on. The first thing to diagnose, is if you have any refrigerant inside your a/c system. Which from here it looks as if you don't- (because you state compressor not coming on). Fix the a/c and see what happens with the fans.

BTW 2001 and 2002 U-vans are notorious for condenser leaks at lower passenger side mounting bracket- if your condenser has never been replace (OEMs are aluminum colored, replacements are black in front) then there is where I'd look for leak first.

12-27-2016, 04:41 PM
Thanks alot for the feedback. Yes I have considered about there being low pressure refrigerant, in which case the low pressure switch in the compressor would disconnect the compressor. I will have to figure out how to check this or take it to the shop. The thing is that i see in the diagram i posted that there's an ac refrigerant pressure sensor connected to the pcm that i assume would trigger a code if there were low pressure. Also the AC was running pretty cold up until just before this whole problem.

So i still suspect possibly an electrical issue. Hoping though it's just low pressure refrigerant.

12-27-2016, 06:42 PM
No codes are ever set for low refrigerant pressure- refrigerant pressure changes with temperature- so if it is below freezing out- there is low refrigerant pressure, and you would not want a code for something that happens every time ambient drops below freezing. If fan(s) work with engine temp, they should work with a/c if and only if a/c needs them- if no a/c pressure, or low a/c pressure, then fans do not come on- simple as that- you don't need the fans when running highway speeds- so that is why they let the a/c head pressure determine the need for the fans.....

12-28-2016, 12:08 PM
Thanks again for your feedback, a great help. I'm reading that codes P0530 - P0533 are all supposed to be related to refrigerant pressure, so it says. Particularly P0530 refering to low refrigerant pressure.

12-29-2016, 05:05 PM
well still working on this. I want to do as much trouble shooting as i can before resorting to taking my vehicle to the shop.

I am no pro but really just trying to figure as much as i can about my own vehicle. I've done my research and found out a few things. About the AC, I was always under the assumption that any car ac routinely needs an ac charge because after time the refrigerant just gets used. From what I understand now, a vehicle AC system is supposed to be always sealed. The refrigerant can be used as long as it does not escape through a leak. So a vehicle only needs a recharge if there's a leak in the system.

I was hoping that my issue could simply be a matter of buying a DIY can of refrigerant and filling my ac up. Evidently it is not so simple. Rather there will have to be pressure testing with proper gauges and troubleshooting where the leak is, then repairing wherever it's leaking. Only then could it be refilled, and which is a very careful procedure to avoid overfilling which could damage the compressor. And there's the DIY refill cans with leak sealants added which is kind of a gamble because these sealants can also clog the system and do more harm than good.

On top of that the DIY refill kits, according the directions I've seen, require that the fans and compressor are already running, which in my case they're not. Some folks hook the compressor up to the battery directly but this they say can damage the compressor if it's engaged without adequate oil, which it likely is when its on low pressure.

A vehicle like mine where the fans and compressor aren't running when the AC is turned on could either have a refrigerant leak somewhere in the system (could be leaking from several parts), a bad compressor (or a bad clutch), or a bad electrical connection (bad low pressure switch, connectors, fuses, relays). At least a dozen different things to check.

Today I got some aligator clips for my multimeter probes and tested the voltage at the compressor again, this time by sticking a paper clip in one side (did alot of digging before i learned that trick). Again I am getting around .14 volts. So I am sure theres no power there. I found these videos here this guy does a nice job step by step showing how to test every point in the electrical system, which is like a dozen check points itself.


Looking forward to updating this fix to as not to keep folks left hanging who are searching for the answer on how to fix their chevy venture. It's just wonderful when folks open a thread, get feedback, and then never follow up with a conclusion to tell what the heck ever happened. Most of the threads on these forums are like that, just a dead end with no solution.

12-29-2016, 05:21 PM
If you buy a refill kit- attach the gauge hose to the low side port (do not open can valve) and read the system pressure, you'll know if it has any refrigerant pressure in it. If it reads zero- all refrigerant is gone. If it reads above 47 psi, then you have at least enough to activate the compressor. From here- I will say you have less than 47 psi, since compressor does not come on.

If all refrigerant is gone- you have a massive leak- listen for hisses if you decide to add some.

You can add to a system where compressor is not running- the pressure from the can will pressurize the system to activate the compressor.

Also you can have a system that reads 80 psi and only have 5% of the needed refrigerant in it. This is why it is important to "weigh in" the refrigerant- to get the correct amount in the system.

01-15-2017, 06:52 PM
If you buy a refill kit- attach the gauge hose to the low side port (do not open can valve) and read the system pressure, you'll know if it has any refrigerant pressure in it. If it reads zero- all refrigerant is gone. If it reads above 47 psi, then you have at least enough to activate the compressor. From here- I will say you have less than 47 psi, since compressor does not come on.

If all refrigerant is gone- you have a massive leak- listen for hisses if you decide to add some.

You can add to a system where compressor is not running- the pressure from the can will pressurize the system to activate the compressor.

Also you can have a system that reads 80 psi and only have 5% of the needed refrigerant in it. This is why it is important to "weigh in" the refrigerant- to get the correct amount in the system.

Thanks again for the feedback. I have put this AC issue aside for a few weeks since it is January and can live without AC. But I have read that AC issue should be fixed ASAP because if there's a leak moisture can get into the system and create more problems.

I got back to it today and wanted to do as much testing as I could with the multi meter. I don't have a pressure gauge manifold. I managed to get to the low pressure switch/sensor which is located under the air box, had to remove the whole air box which was a PITA to put it back. But I uncovered the pressure switch. There was the required 5 volts to the switch and ground was good, but there was no continuity on the switch. Another indication of low pressure.

If it's low pressure I was wondering if there's at all any possibility that it could just need a recharge. Perhaps if it were a very slow leak then a simple recharge would do the job. I have read that a small amount of leakage is normal in any system over the years. I've had this vehicle for 8 years and never had any service on the AC.

But the AC seemed to stopped working suddenly. As I recall it was blowing as cold as usual up until it suddenly stopped working. I assume it would have gradually become less cold before the low pressure switch would disengage the system.

So I was wondering if I could just add some refrigerant to see if the AC clutch engages. You have hit upon just what I was considering to do - get some refrigerant and see if it will take a charge. But everywhere I've looked the instructions say the compressor must be engaged already while adding refrigerant. You are saying that I can add to a system where the compressor is not running and the can's pressure could cause the compressor to engage. I have read about this in one place and it says that the radiator fans must be running for this to work. On my vehicle the radiator fans are not turning on until the coolant temp reaches about 226F. Can I add the refrigerant without the radiator fans running? Or Should I let the vehicle run and heat up until the radiator fans turn on ?

Regarding how much refrigerant to add, the Haynes Repair Manual simply states "Never add more the 2 (12Oz) cans of refrigerant to the system. Seems rather vague. You mentioning weighing the refrigerant, I assume using a scale to measure how many Ounces. But the repair manual doesn't even specify how many ounces, just "never add more than 24 Ounces".
How to know exactly how much refrigerant to add ?

01-15-2017, 08:40 PM
First of all, your "switch" is a pressure transducer-used for variable measurement of system pressure- there will be "no continuity"- just a variable voltage feedback to the ECM. You know it is not a switch because it has three wires. NEVER jumper a three wire transducer, you can cause ECM damage. Pressure transducers were introduced in mid to late 90's on most cars....

Yes you can add refrigerant without coolant fans and without compressor running. Again, static pressure is your key- once you attach refill kit gauge- you'll know what your static pressure is-- from here I'm betting it is below 47 psi, at a warm ambient-say 70 degf or so. If this is true, then you have about 3 or 4 ounces in your 2+lb system. So adding a whole can should make the compressor engage.

01-22-2017, 02:57 PM
I am considering to buy these items: gauge separately with a couple cans of straight r134a



Most of the refill kits that come with the refrigerant and gauge like AC Pro all seem to have stop leak additives. I see cautions about adding the stop leak additive saying it can clog the system and make things worse. And that repair shops will charge you even more if you have used the additives because it spoils their equipment. So I'm really uncertain about using it though many people report good results. What is your suggestion on this ?

I am assuming that I could get some idea whether there is any pressure in the system by just pressing down on the pin in the low side pressure valve, which I did. But no pressure was released. If there were pressure wouldn't you be able to check it this way just to see if its not totally flat ? (OK afterwards i read it's not adviseable to do that, unsafe & illegal to release refrigerant)

If I do use just the r134a alone, don't you still need to put oil back into the system ? If the low pressure switch, transducer whatever shuts down the compressor to protect it when refrigerant is too low, wouldn't you need to add oil back into the system along with the refrigerant ?

01-22-2017, 06:18 PM
If you are dead flat- which it sounds as if you are, then you need to find your massive leak- so just adding some refrigerant, a little at a time will be needed, in order to find your leak- a good sniffer, or dye check is needed, or it may even hiss at you-- did you ever decide if your OEM condenser was ever replaced? They are notorious for leaking at passenger side lower mounting bracket- it tears away from the tank- cracks from vibration- and you can see the leak by just popping the hood and looking at the oily residue.

01-22-2017, 07:23 PM
(Wow I didn't realize you had already replied and pinpointed exactly the issue ! Yes it is the condenser. I can see the oil stain all over the bottom corner on the passenger side, just like in the picture here I found online)

After further online research I found out that 01' & 02' Ventures have a common issue with the condensor leaking in the lower corner where the attachment bracket is on the passenger side. Someone posted a picture showing where you can see the leakage on the condenser. I checked my van and that's exactly what I have.


Not good news. People talking like $700 to repair. At least I know now what the problem is and I didn't have to waste time and money buying refrigerant, dye, gauges, etc.

Coincidentally I had just replaced the radiator fan motor on the same side only a few days before the AC went out. When installing the motor I was noticing that the fan was not spinning as freely by hand as the other side fan. It seemed to wobble slightly. Before removing the failed fan motor I had not thought to notice how it was spinning by hand, so I was not able to compare before and after with the new motor. But when I powered the fan it seemed to run smoothly, so I figured all was good and put everything back together. The fact that the AC went out just a few days later has me wondering if the fan is creating some excess vibration there that caused the condenser to break faster than it would have if the fan were running perfectly. I really don't know if that's an issue. All i can tell is that the fan seems to spin as it should.

Anyhow, the van is 16 years old and has 205K, and this issue happens on most of these vans sooner or later it seems. They say that the bracket is attached through the condenser and weakens causing the leak. Someone said the "new design condenser does not bolt through that bracket anymore." So hopefully when I do fix this it will last and whatever may be the situation with the fan would not be an issue.

Do you think it may be a worthwhile do it yourself job ? I did replace the fan motor and had to remove the assembly. That was enough of a pain. It looks like you'd have to pull out the fan assembly and radiator to get to the condenser. I imagine you have to evacuate the system, tear out those parts & replace then recharge the system. I'd need a vacuum pump, gauge manifold and a bunch of stuff. I don't know, this fix could be way out of my league.

Do you think it's too difficult job for most ? Any suggestion on what should be a fair price at the shop ? $700 ?

01-23-2017, 09:49 AM
Just the fact that you worked with the fan assembly, (moved it etc) was enough to finally crack the weak point.

That first photo you shared was one of mine back in 2005 btw.

I've changed probably 50 or more condensers on these vehicles- surprised yours lasted that long- you can do it okay, just have to pull fan assembly out first, then radiator/condenser together comes out- tranny lines can be a pain- need to remove spring clips inside quick connects- I've replaced condenser without pulling radiator- but that too is a pain- hard to get condenser line bracket off- only tried it once- cost me much more time, then pulling radiator. ECM comes out and laid back, air box is removed to get to condenser connections. Have yet to see a replacement condenser where you did not have to bend the heck out of the mounts to make it line up with bolt holes- more time. And yes, there is no mount hole at weak vibration point on replacements. It all depends on your ability and how determined you are to do the work.

04-28-2017, 08:10 PM
Thanks again for the help. I recently had the condenser replaced by my shop, replaced the radiator as well while in there. Total out the door for Condenser and radiator was $700, not too bad I guess. I'm not of an experienced mechanic so probably saved me alot of headache over trying to do it myself.

Next item on this 01 Venture is a loud rumbling wheel noise which seems to be coming from the rear when driving. Maybe a bearing ???

07-07-2019, 02:13 AM
My solution to this rediculous setup GM plagued us with, was to buy a 4 season wiring harness with relays and spliced it in to the van's wiring harness (with all the wires still connected to the ECU) and wired the both positive wires to the battery. 1 positive was supposed to go to a switched source, but the fans only run for a short duration after shutdown. The harness uses a probe that you gently put through the fins on your radiator. I would recommend buying an after market probe style gauge that you would put near the fan probe if you don't trust the factory gauge. Just be sure you warn anyone under the hood that the fans can come on at any time.

I know i will receive flack about this setup, but if your van is like mine where fixing the a/c costs more than the vehicle's worth, the $35 harness sounds brilliant! I really hope this helps someone out. Believe me, i love my van but it frustrates the crap out of me. So much money into head gaskets, fans, sensors, water pump, alternator, fuel pump and now timing chain! I will fix it again and until the rest of the body falls off! Best of luck, message me if needing advice or clarification on this.

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