'97 Taurus GL Wagon (171k): Weak A/C

3.0Liter Vulcan. Car is self-maintained. A/C was barely acceptable last summer, but this year it seems non-existent (just a hint of cool air). Blend door actuator OK. This is probably going to be a refrigerant leak, no? Can I give it a charge myself (as a preliminary fix)? I've never done anything with an A/C system before, but I've done most everything else on my cars (last big job was replacing intake gaskets on my '02 Impala).

You can do the job yourself, but to do it right will likely require you to purchase or borrow more tools. If you want to do the job correctly, you'll need a good gauge set that monitors both the low pressure and high pressure sides at the same time. You'll also want a vacuum pump that you connect though the guage set. You'll need some form of leak detector, best would be the gas detector, but a dye set would probably work long-term. You'll also need some means of injecting a few ounces of oil into the system after pulling the vacuum on the system.

From what I've heard, it's still illegal to vent R-134a into the atmosphere, which you'd likely be doing with the vacuum pump. There's supposedly some loophole in the law that allows non-licensed folks to purchase the cans of R-134a, but supposedly it's still illegal for non-licensed individuals to service the A/C system. I haven't looked in to that though to determine if it's really the case.

Of course you'll want to start with the gauge set, you might find that the system is just a few ounces low, but low enough to cause the pressure switches to prevent the clutch from engaging. You could have the proper amount added while monitoring the gauges and see if the system works. If you get the clutch to engage, watch the high and low pressure needles to make sure they aren't bouncing around which could indicate other issues, like restricted orifice tubes or a worn compressor.

-Rod

Do you know, offhand, if Harbor Freight has those tools and if they of adequate quality? I think I've seen the gauge set in their famous flyers (and maybe a vacuum pump), but I don't remember seeing a gas leak detector or dye set (or means of injecting oil - or is that just a syringe or oilcan?).

The gauge set is something I've been meaning to pick up anyway so that I can more precisely hound my landlord to refill his heat pump - which has been leaking refrigerant now for over a decade (a violation of environmental laws I'm sure)! It needs refilling 3 times per year. If I had the gauge set, I'd probably find out it needs even MORE frequent re-fills...

I gotta get out of this place!

Harbor Freight does sell the gauge set and vacuum pumps. They have very inexpensive pumps that require an air compressor, and more expensive versions that run off house current. The gauge set will allow you to charge the system as well, and if you get the cans of oil that connect to the gauge set as well, you won't need an injector. Likewise, you can buy cans of R-134a that already have the dye in it.

The gauge set may not have the proper size fitting to work on the heat pump.

-Rod

Yes, it is correct that the fittings for automotive ac systems and non-automotive systems use different types of fittings, with the latter having both the high and low sides threaded, requiring either two sets of gauges or adapters ONLY if they are the same refrig. You don't want to mix different refrigerants with the same gauge set. There may be some allowed sharing, I just can't remember, but definitely not older refrigerants like R-12 with newer refrig. like R-134a for a lot of different reasons like incompatibility of the refrig. and the oils and the laws governing their handling.

It certainly does seem inconsistent to allow non-certified purchase and use of R-134a and the components to those systems if the law says they can't touch ac systems. I do know R-134a was the first step to replace R-12, R-22, R-502 and others as a "less ozone depleting" refrig., but I think it turned out to be not as good as they hoped and it too has some environmental issues. I don't know much about the legal side of this stuff other than the big gov. move to eliminate the older refrigerants to reduce and eliminate CFC's and other ozone depleting compounds. Unfortunately, there will be for a very long time continue to be accidental and illegal discharging of ALL refrigerants.

Your landlord, Colt Hero, is nuts to have some hack recharge the heat pump several times every year. Either the pressurized system is in such a state of decay that it is futile to recharge and repair, or the problem is not being dealt with properly. That to me would be a reasonable, reportable offense due to what seems to be an obvious case of deliberate neglect. Let me put it to you this way, if it was an industrial or very large commercial operation doing that kind of crap, they'd be in trouble. It sounds to me like that is an older system at your place which would more likely have R-22 in it. The gauge set for that you would probably have to borrow due to law and compatibility issues. You also need to know what you're doing. Unfortunately, that comes from experience, which I don't have enough to be helpful enough for a home system. I'm ok with the auto systems. I know enough to do enough, but enough to get in trouble if not careful.

Rod's right that your car and even your home systems can have a problem more involved than a simple loss of refrig. due to minor leakage that a stop leak might handle. If the orings need replacing, even for that "doing it right" can get involved. Replacing components even more involved as warranties and just good measure require replacing the air dryer/accumulator and the evaporator orifice, and cleaning the system. The normal way requires special equipment, but I have seen at AZ a new product that will take care of that step. Boy if it really works, that would really be worth the money!!!

Good luck!

So I should have TWO sets of gauges, you're saying - IF the two systems use different refrigerant. This is because of residual gas inside the gauge that could mix with another system when used??? The Taurus is a '97 and is all-original. This rental house was built in either '93 or '94, so the heat pump (Goodman) was probably new from that year. It's possible the two could have the same refrigerant, but how would I know?

As far as re-charging the heat pump, I've seen the 'handyman' do it several times. Tell me (if you can) how my observations of his work might relate to doing the same job on a car:

1.) His set had three hoses and two gauges. The red hose was the 'high side' hose and the blue was the "low side" hose. The third hose was connected to the refrigerant source (tank).

2.) He told me if you can't tell which connector on the unit is the "high side" (they're usually labeled), attach the "high side" hose from the gauge to one of the connectors. The one that makes the high side gauge spike up near (over?) 100 psi is the "high" side. Make sure NOT to test with the "low side" hose (because it could damage the gauge???).

3.) With all the hoses connected AND the unit running full blast, look at the "high side" gauge. Add 20 to the current ambient temperature and this is where your gauge should be reading (psi). Example: it's 75 degrees outside, so the gauge should read 95 psi. Read the inner (Red?) circle gauge, NOT the outer (black?) gauge.

4.) If the reading is low, the unit will automatically suck refrigerant out of the tank.

5.) Be VERY CAREFUL removing the gauge hoses from the unit. You can experience frostbite burns to your hands from escaping refrigerant if you don't have the special $50 fitting that connects between the unit and your hose line (high side line). This fitting (or valve) eliminates the long stretch of test hose that can hold residual refrigerant which can BLAST OUT when you remove it. It is well worth buying (or looking for a test gauge that comes with it).

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Once, last year I think it was, the landlord had a "pro" look at the heat pump. The diagnosis was what the handyman had been saying all along: condenser/coil leak. $800 to fix/replace, or replace the entire unit. Landlord did nothing and the "pro" subsequently said he would never deal with the landlord again (trouble with payment for his work, I think it was).

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I'll have to drop by Harbor Freight and take a look. Always like going in that store. I know that most of that merchandise is junk, but they sell so many interesting things (and so many practical things that are are so inexpensive) that it's just fun to shop there. The handyman told me he bought a roofing nailer there that he didn't expect any real use out of - but it's been really good ... lasting several years now.

First off, I really don't expect the two systems to use the same refrigerant. I expect the heat pump to use R-502 or something newer, but it could still be using the older R-22. There should be a spec. plate, typically on the back of the unit where the copper line set enters the outside unit. Often the connections are on the outside, but since you've seen work done on it I assume you know where they are. It sounds like you have a really good grasp of things, but I'll add a few things for everyone's benefit.

There are two copper lines, each with a shutoff valve, the low side, which will be cold, sweaty and frosty when working correctly and the larger of the two, and the high side, which should be very hot and much smaller. The size of the pipes holds true for auto systems too, but may not be as obvious if not looking in the right places. You may be able to use the same gauges and manifold if the auto and home systems use refrig. in the same family, but you will either need to have hoses that can accept adapters to convert to the other systems (which I don't know if they already exist or you would have to fabricate yourself), or you buy a hose set to fit each different system you work on while using the same manifold and gauge set.

The last time I worked with HVAC techs on the home and commercial units was over ten years ago, so my recollection is not all there, and I didn't work with them enough to gain the vast knowledge they had as the operation of these systems is a bit of smoke and mirrors, especially when they are not working right!!! I'm fuzzy on if all of the hoses already came with check valves or not back then, but I don't remember having an added on check valve with all of the hoses, perhaps only for certain uses. I always recall there being a small discharge of refrig when disconnecting the hose. That add on does sound smart for full time work.

The procedures you listed sound very good. The only point of concern I have would be that you can still over charge a system even if it is sucking in refrig. on the low side. Like you said, you have to watch the temperature to pressure relationship, but also be sure the system is cooling correctly, like frost on the low side, but not going all the way to and into the compressor. Compressors are for gases not liquids. Liquids don't compress, that's why pumps are used for liquids instead. Frost indicates the formation of liquid refrig. Many systems are incorrectly overcharged by the "repairman" when it has a problem other than too low of a refrig. charge, where he blindly adds refrig. to a system that is "not cooling" when instead of a low charge there is a blockage or other major system problem. This mistake will result in a system with way too high pressure on the compressor high side and something will eventually not like it and give, sooner or later.

Also, for everyone, NEVER EVER TRY TO PUT REFRIGERANT IN THE HIGH PRESSURE SIDE OF ANY AC SYSTEM!!! IT IS EXTREMELY DANGEROUS AND CAN RESULT IN AN EXPLOSION!!!

FWIW, I know Rod likes folks to use all of the correct equipment, but considering all of the basic recharging tools and all in one refrigerant recharging products, if you have a simple low charge, I would think you would be all right using what is out there. I have been ok with it. But, I have additional experience I use to watch for things like dash vent temperature, frosting on the low side/suction line, temperature differential, clutch cycling. Another point on home units but can also apply to auto units, clean evaporator and condensor coils and filters, so that there is proper air flow, is very important and may be the only thing wrong with some systems that perform poorly. Especially with home units, you can have icing occur depending on the air flow restriction.

Lastly, at the top of the Taurus Forum, there is a sticky that few know I penned that Rod posted on ac systems. I really should go back to it and tweak and add to it.

"like frost" you meant "light frost", right? Maybe you could edit that for posterity so the next guy won't be confused.

I'm glad you mentioned the clean coil and filter thing. I forgot about that. I once had this problem on the heat pump years ago. Hosing the coil down solved it. Maybe that's my entire problem with the Taurus. I'll have to look for the coil and filter (if there is one) in the car to see if I can clean or replace either first before getting into the re-charging stuff.

Interesting discussion. Ive looked at Harbor Freight AC pump and gauge sets as an extra so I dont have to carry my Robinair pump back and forth. However the manufacturer for Harbor Freight wouldnt say the pump would achieve or hold -29# so I held off. If you go with Harbor Freight equipment make sure it holds -29# or better so the moisture is evaporated out of the system.

Colthero, you said, ' "like frost" you meant "light frost", right? Maybe you could edit that for posterity so the next guy won't be confused.

I'm glad you mentioned the clean coil and filter thing. I forgot about that. I once had this problem on the heat pump years ago. Hosing the coil down solved it. Maybe that's my entire problem with the Taurus. I'll have to look for the coil and filter (if there is one) in the car to see if I can clean or replace either first before getting into the re-charging stuff.'


You're asking for more detail than I can give with certainty, but I'll add what I can for my posteri'aire and others' benefit.

Most of the time you will see light frost on the cold line at the outside or compressor unit after it's run a bit when adequately. What you don't want is a heavy frost right at and entering the compressor and on the compresser. However, depending on a lot of factors like air temp, rel humidity, duration of continuous operation, etc, etc, you can form heavy frost in locations that would be ok to occur, like right at but down stream of the evaporator. If there is not enough or no air going across the evaporator, which creates too low of a heat load, the evaporator will "ice up" or freeze. That's very bad and will take quite some time to fix, usually just by melting and correcting the cause of the inadequate air across it.

BOTH coils can become clogged, but the condenser coil found outside or in the front of the car are the most
susceptible to debris buildup. Since the ac condenser tends to be the first in line to get air flow through it when driving, all the road junk and bugs especially really build up in it. The home condenser gets grass and other yard debris in or against it. The inside evaporator coil can clog or get dirty but is much less likely due to its enclosed location, but it will get dirty with a missing or bypassed filter or greasy air or rodent's nest, etc. The worst case of a condenser blockage I've ever seen was on the roof of a Burger King where the units sit and suck up all of the grease laden air that is vented to the roof from the burger grill. What a mess!?! At my home, my biggest problem with the condenser coil fins clogging is from the clothes dryer exhaust right behind it. The fabric softeners and the lint make a slightly sticky, gooey stuff that gets sucked into the coils. I have to use a combination of soap and a powerwasher with great care not to bend over the fins, to get it clean nearly yearly. I swear I need to put a screen over it to avoid all of that because it takes a lot of time to do. I'm hoping the screen I can just take off and clean and put back on and not have any buildup at all on the coil.

Sixseas, how long should one see if the ac system will hold -29 psi? I don't remember beyond waiting for the pump taking a long time to do it.

Interesting discussion. Ive looked at Harbor Freight AC pump and gauge sets as an extra so I dont have to carry my Robinair pump back and forth. However the manufacturer for Harbor Freight wouldnt say the pump would achieve or hold -29# so I held off. If you go with Harbor Freight equipment make sure it holds -29# or better so the moisture is evaporated out of the system.

I have the Harbor Freight gauge set and the little $10 diaphragm pump. The pump will get to around 31-32 psi of vacuum on a tight system according to the gauges. The guages actually appeear to be of pretty decent quality, so I don't really fear that they are off by much. My 27 gallon compressor runs pretty much the whole time getting to that point though. Once there, I closed the valves on the gauge set, shut off the compressor, disconnected the pump, and let it sit for a couple of hours at vacuum to make sure I didn't have leaks. Everything seemed fine so I charged the system with the proper amount of R-134a which also got the pressures where they should be.

I didn't get much oil out with the pump (maybe a 2 inch spot on my garage floor), and I only had the system pumped down because I changed out a leaking Shrader valve. The A/C has worked great for the year since then.

-Rod

Also remember vacuum is relative- you will "pull less" at higher altitudes. Atmospheric pressure at your location, read in inches or mm of Hg, would be a perfect vacuum reading.It should not drop more than 1"/5minutes. Most leaks larger than that should be visible by dye or oil residue.

Thanks thats really good to know. AC is really important to me as I cross the Mojave several times a year I 15 between Baker and Vegas, and I 8 through Imperial valley can be brutal if my AC isnt up to it.

I had been putting my Robinair 15234 pump in the suitcase on the return trip. Last trip TSA held the pump and gauge set had to have friend pick it up at the airport. So if the small Harbor freight pump will do -30 @ 4 feet above sea level Ill pick one up. Sorry to get side tracked from the weak AC problem but thats a big help solved a problem I just ran into.

The altitude where I used the pump is somewhere around 840 feet according to GPS.

-Rod