AC Problems, 1987 Coupe

kirkeric · 07-25-07, 10:27 AM

Hello,

I have another thread titled "Removing Dash from 1987 Coupe" but the underlying issue is AC and presume that is why I've gotten some limited responses from our good man Jester.

I have an AC problem that was originally diagnosed as leaking o-rings on compressor, bad wiring connecter (fixed) that was prevently compressor from kicking in, and bad evaporator core.

The leak is minor since it began blowing cool air once I fixed the wiring problem (just replaced connector pins).

My problem is the fan blows very low, even on high. Jester asked some good questions that I will summarize here.

Fan speeds are noticable between lo, med, high.

Fan works the same way even in heat mode.

All functions, such as bi-level, defrost, etc work.

The only issue seems to be that the fan just doesn't blow well enough.

I am not convinced that the evaporator core is bad since I DO have cold air, just not enough.

My assumption at this point is that the blower needs to be replaced.

I appreciate any feedback that might help, to include how to do the replacement. That was the original reason for the other subject title was that I know I need to remove the dash to replace the blower and or the evaporator.

I thank you all ahead and thank you jester for your assistance.

Eric

kenwa · 07-25-07, 01:36 PM

You've described your problems much better in this thread, Eric. I think you'll get more help this time. BTW, welcome to CAC.

It could be your fan, but my experience is that they either work or they don't. This sounds to me like an obstruction or clog. The person who told you your evaporator needed to be replaced, did he say anything about that? A clogged evaporator doesn't need to be replaced, just cleaned.

Get a small thermometer and stick in in a vent, and drive down the road with the A/C on full. Idling won't do because the compressor doesn turn fast enough. If your only problem is lack of air flow, the air temp coming out of the vents will be very low, probably in the 40's. This is because the evaporator has plenty of time to cool the slow moving air as it goes through. BTW, don't crash while looking at the thermometer.

Also, do you get more air flow the faster you drive? (With A/C not on recirculate, that is.)

Let us know what you find.

Ken

kirkeric · 07-25-07, 01:41 PM

Ken,

Thanks. I will try the thermometer. The fan speed/air output increases only slightly with speed, hardly enough to recognize. I do know that on an 85 degree day yesterday, I went about 55 for a few mins and it was just nearly enough to become almost comfortable. Enough to know that with more airflow, I believe I'd be good.

So, while I check this out with a thermometer, can you provide any info as to how difficult it would be to either replace the blower or check for a clog?

I like the clog thought because that sounds cheaper for sure and depending on your answer, possibly easier to fix.

Oh, I don't believe I have a recirculate switch. Hardly any controls but 2 sliders from cold to hot and from Max Cold to defrost, etc.

And thanks for the welcome to CAC.

Thanks,
Eric

Quote:

Originally Posted by kenwa

You've described your problems much better in this thread, Eric. I think you'll get more help this time. BTW, welcome to CAC.

It could be your fan, but my experience is that they either work or they don't. This sounds to me like an obstruction or clog. The person who told you your evaporator needed to be replaced, did he say anything about that? A clogged evaporator doesn't need to be replaced, just cleaned.

Get a small thermometer and stick in in a vent, and drive down the road with the A/C on full. Idling won't do because the compressor doesn turn fast enough. If your only problem is lack of air flow, the air temp coming out of the vents will be very low, probably in the 40's. This is because the evaporator has plenty of time to cool the slow moving air as it goes through. BTW, don't crash while looking at the thermometer.

Also, do you get more air flow the faster you drive? (With A/C not on recirculate, that is.)

Let us know what you find.

Ken

G Winter · 07-25-07, 07:12 PM

You say you don't have a recirculating control. On most GM vihicles the air recirculates on max air. I also believe you may have an obstructed evaporator,or possibley a air door that is sticking. The evaporator naturally gets wet so dust may turn to mud and build up.

Glenn

kenwa · 07-25-07, 08:04 PM

Eric, you won't have to pull the dash. The evaporator and blower motor look to be accessable from under the hood. If true, this would be the first time I've heard of something being relatively easy to get to on a Corvette.

The whole thing is on the passenger side firewall, with the blower right behind the right front tire. See attached drawing. If, and that's a big if, the blower comes out as easily as it looks (on my 96 anyway), then with a mrror you should be able to see the evaporator.

I noticed that my 96 apparently has an air filter in there. You'd think it would be accessable...

Ken

greenstingray · 07-25-07, 08:51 PM

Is this a climate control car? If it is check the module under the hood on top of the evaporator. This module controls the fan speed;check your fan by sending 12 votls directly to the fan and see if it goes on high. If the fan goes high then the problem may be with your module. This module was used on cadillacs,buicks, pontiacs; Get the part number and go to acdelco.com check the cross reference and see what other cars use the same module. I would then go to your local junk yard and look for a car with that module. It should not cost that much from the junk yard try it in your car see if it works.

greenstingray · 07-25-07, 09:01 PM

BTW this the module I was referring to in my last post;

http://www.ecklers.com/product.asp?p...dept%5Fid=1186

kirkeric · 07-25-07, 09:21 PM

Glenn,
Thanks. That sounds right, given the symptoms. Now, how do I get to all this? Is there a removal procedure for the dash?
Thanks.
Eric

Quote:

Originally Posted by G Winter

You say you don't have a recirculating control. On most GM vihicles the air recirculates on max air. I also believe you may have an obstructed evaporator,or possibley a air door that is sticking. The evaporator naturally gets wet so dust may turn to mud and build up.

Glenn

kirkeric · 07-25-07, 09:34 PM

Thanks. I just saw the other messages which better describe the location. I was checking this on my cell phone and didnt see all the other replies.

THanks,
Eric

Quote:

Originally Posted by kirkeric

Glenn,
Thanks. That sounds right, given the symptoms. Now, how do I get to all this? Is there a removal procedure for the dash?
Thanks.
Eric

G Winter · 07-25-07, 09:45 PM

Be sure to check all the easier options first. If other options aren't the problem, then worry about pulling the dash.

Glenn

kirkeric · 07-25-07, 10:15 PM

Glenn,
Thanks and I'm with ya on that! I'm not dying to pull the dash. The Chevy dealer wanted to charge me 1400 bucks to pull the dash and replace evap core. sounds like they didn't need to pull dash after all?
The other gentleman mentioned that fan module. Will I have that on my year?
Thanks!
Eric

Quote:

Originally Posted by G Winter

Be sure to check all the easier options first. If other options aren't the problem, then worry about pulling the dash.

Glenn

kirkeric · 07-26-07, 07:14 AM

Thanks for the image. There must be another one that actually shows it under the hood or you just know from experience.

Hopefully it's right where you describe. I will check tonight. Now, another question. You mentioned being able to see the evaporator with a mirror. Does that mean that the evaporator can ONLY be seen from under the hood and not replaced (if necessary)?

Will I have enough access to it to at least clean it and all?

Thanks,
Eric

Quote:

Originally Posted by kenwa

Eric, you won't have to pull the dash. The evaporator and blower motor look to be accessable from under the hood. If true, this would be the first time I've heard of something being relatively easy to get to on a Corvette.

The whole thing is on the passenger side firewall, with the blower right behind the right front tire. See attached drawing. If, and that's a big if, the blower comes out as easily as it looks (on my 96 anyway), then with a mrror you should be able to see the evaporator.

I noticed that my 96 apparently has an air filter in there. You'd think it would be accessable...

Ken

kirkeric · 07-26-07, 07:22 AM

I don't believe mine is climate controlled. I just found this link to someone selling one on the net and it is described as climate controlled. The one picture of the dash is not a real close-up but it is enough to tell that it is not the way mine looks. http://www.vettefinders.com/index.cf...e_for_sale.htm

Mine has just 2 slider switches with the fan speed dial on left side and the defrost dial on the right. The attached image I found is exactly what my controls look like. So clearly, the above link is a climate controlled car and mine is not.

The sliders: Top one goes from MAX, NORMAL, BI-Level, etc. The lower goes simply from Cold to Hot.

Eric

Quote:

Originally Posted by greenstingray

Is this a climate control car? If it is check the module under the hood on top of the evaporator. This module controls the fan speed;check your fan by sending 12 votls directly to the fan and see if it goes on high. If the fan goes high then the problem may be with your module. This module was used on cadillacs,buicks, pontiacs; Get the part number and go to acdelco.com check the cross reference and see what other cars use the same module. I would then go to your local junk yard and look for a car with that module. It should not cost that much from the junk yard try it in your car see if it works.

kenwa · 07-26-07, 11:09 AM

Quote:

Originally Posted by kirkeric

Thanks for the image. There must be another one that actually shows it under the hood or you just know from experience.

Hopefully it's right where you describe. I will check tonight. Now, another question. You mentioned being able to see the evaporator with a mirror. Does that mean that the evaporator can ONLY be seen from under the hood and not replaced (if necessary)?

Will I have enough access to it to at least clean it and all?

Thanks,
Eric

I don't really know what you'll find in there or how much room you have. I haven't been in there myself, although I think I'll look into the filter replacement procedure on my 96. My guess is that you will have room to put a flexible vacuum cleaner hose in there if you need to. Now, whether you should do that, I don't know.

Key West Jack · 07-26-07, 01:10 PM

This is the one for models without the climite control:

http://www.parts123.com/parts123/yb....0f~Z5Z5Z5FAXJN