Bonneville blower AC climate control problem

[19Bonneville94SSE]

Hey guys I had to re-register my name because it wouldnt send me my password. Anyways whats up its been a while since I was last here. I have a 1994 Bonneville SSE with 206,000. The air from the vents seems to be pretty scarce. Sometimes, and this has only happened when I was on the highway, the air will pretty much shut off, although I hear the fan blower at high speed... I read through the other forums on this kind of issue and I have no idea what route to take. I have already done the core cleaning as told so in one of the other forums, lol the one thing I wasnt told was that when I use the hose to rinse it off that it was all going to end up with a lake in my car!!! haha Anyways that didnt work and I am almost out of ideas... Oh yea when I am driving on the highway, and when the airflow does get scarcer and scarcer all I have to do is hit ECON and wait for the AC compressor to shut off, and then hit AUTO again to get the compressor running again and the air will come out stronger again... but nowhere NEAR what it should be. AHHH I think I should just get rid of the car toooooo many damn problems!

[randman1]

It sounds like you have a broken or disconnected vacuum line. The air diverters are controled by a vacuum source and will default to the windshield vents in the event of a vacuum loss. You have a little tank on the firewall next to the master cylinder that holds vacuum pressure during different running conditions.

Because you can still hear the blower running at the same speed, it's still running... just now blowing out the dash vents. Check the line at the tank on the firewall.

[19Bonneville94SSE]

all right, I checked and double checked the vacuum lines and I couldnt find any leaks at all. I did replace those lines earlier this year though. I did have this problem last year. I dont see how a leak in the vacuum line would cause the problem, only because once I hit ECON and then hit AUTO again the air blows a little harder ya know... is there any sensor that could be shot??? Im like out of ideas here lol... do you have any other ideas randman? Thanks for your help too!

[randman1]

Well, that's the most common problem and area. Can you verify my theory? That the air is being directed to the windshield vents rather than the dash vents?

The other place where there could be a vacuum problem is right at the HVAC programmer.



Here's the programmer. The purple line is the source and the other colors go to the diverters. I've heard of the "connector" where the lines enter the programmer softens and partally blocks the vacuum from doing it's thing correctly. I've only heard of this twice. All other times have been the line at the tank.

Do you happen to have a vacuum gauge??

[19Bonneville94SSE]

hmm... maybe I will just replace the line again for the hell of it..., but also to answer the other question, it goes out the mid-level vents too, I can choose windshield and it will go to windshield, I can choose mid-level and it will go there so that part is working fine... maybe it is because I punctured one of the vacuum lines... it is definitly possible! I will check that tomorrow or sometime this week. Just another question where is the programmer located??? Thanks so much for your help again! There are some damn nice people here!

[randman1]

I'll try to explain it:

A vacuum source to the purple line is dristributed to the air diverters through solenoids (silver relay looking things in the pic). As long as you have an adequate vacuum source, the diverters are are held open by the vacuum pressure. If there is a vacuum loss, which I think is what your problem is, air flow will be diverted to the windshield vents by default because of the design of the system. The tank is there to retain a steady vacuum pressure as there are changes to the vacuum in the intake manifold as you drive.

Since you already cleaned the evap core, this is the most likely cause.

Sometimes, and this has only happened when I was on the highway, the air will pretty much shut off, although I hear the fan blower at high speed...

At this point, feel if the air is coming out the windshield vents.


the HVAC programmer is located above the passenger's hush panel (kinda behind and below the glove box). It normally just looks like a black plastic box but the top cover was removed for the pic.

[19Bonneville94SSE]

hmm I will have to try that... I will also have to check where the air flow is going when I am drivin on the highway although that wont be until thursday. I will definitly let you know what I find out! Thanks for your help!

[19Bonneville94SSE]

ok the AC level lowered itself again BUT it was not coming out any other vents... do you have any other suggestions?

[randman1]

Here's what can cause your problem:
Blocked EVAP core - you already cleaned that
Air flow directed to non-selected vents - you say that air is not directed anywhere it shouldnt be
Blower Control Module failure - you would hear the blower change speeds or would not work at all
Blower motor not working properly - same as above

I feel very strongly that you either have a simple vacuum leak or your blower motor is on it's way out.

[kalafre]

Is it possible that the fan itself is loose on the hub? You would lose air flow but still hear the blower motor turning. Just grasping at straws

[19Bonneville94SSE]

well im just confused because it really really sounds like the blower is going at full speed when it does this... well its not real good in the first place BUT when it decreases to almost nothing the blower fan sounds like its going strong at full speed, once I hit ECON and let it shut the ac compressor off and then hit AUTO again it comes back out heavier again... maybe it is a vacuum leak BUT I dont understand why its doing what its doing... and it ONLY does it when I am at a constant speed of 55 or higher, I can have the AC on for like 2 hours driving at 35mph but once im on the highway about 20mins later it slows itself down... but like I said the fan is at full speed!!! wow im hell of a confused!

[19Bonneville94SSE]

and I dont THINK it does this when the heat is on

[randman1]

I'm not sure what else to tell you other than you're probably going to have to test some things out. Get yourself a volt meter and a vacuum gauge and dive in.

It would be very odd that you experience this problem with the AC but not the heat.

[19Bonneville94SSE]

I know right? Trust me lol I bought this car with 175000 out of an auction two years ago, it was a POS, a RUSTBUCKET!!! Now there is not one bit of rust, almost new interior and basically the whole car was rebuilt by me... Ive come across some of the most F'D up problems it is unbelieveable... This is yet just another chapter out of a book.

[19Bonneville94SSE]

Ok well I have an idea, it is a longshot but if it works I will let you know. I will try it within the next few days.