97 Suburban HVAC issue

[another Todd]

With the blower fan off or on low, the AC compressor will engage and defrost/heat/vent controls all work correctly (except that it shouldn't with the fan off). bump the fan any position above low and the AC compressor cuts off and the heat/vent/defrost controls do not work. I figured since the fan has to be on for the AC to work, the switch must be bad + it felt a little funny like it didn't turn smooth. Replaced the switch with new and the same problem occurs. Any suggestions?

 

[toyota62]

Hi Mate.
yes it is the HVAC control head unit.Seen few in the past does the same thing.1997-2000 models had the problem as you described above.
Chees.
Bob,Oz.

 

[another Todd]

By control head, you mean the controler in the dash below the radio with the knobs for blower speed, temp, and defrost/vent/heat controls? I've read on other sites people with the same problem replace that part and the problem persisted.

 

[another Todd]

I ordered the HVAC control unit today from Rock Auto. $158 shipped for the OEM GM part. The local stealership wanted $294 for the same part. This is a guess, I'll post how it turns out.

 

[another Todd]

The part came but it looked like it had been installed before, so I e-mailed Rock Auto and they will send a new one when I send back the new(used)one.

 

[scott37300]

I would have tried it out even though it looked used to see if that was in fact the problem, since in your other post you said it was a guess.

 

[another Todd]

I finally got around to installing the replacement today. Astonishingly, the replacement sent by Rock Auto had also been opened and resealed, but unlike the first one, didn't look like it had been previously installed. I installed it and it cured the problem. Scott 37300, I did try the first one and it didn't work, in fact, it worked worse than the original. All is well now. I should comment that I think Rock Auto's customer service in this case was excellant. Their prices are hard to beat also.

 

[willix]

I have heard of Rockauto sending used parts before. This tells me to never purchase from them. Its too bad they have some good deals.

 

[another Todd]

I can't knock Rock Auto, they promptly made it right and paid for the return shipping and the shipping of the replacement, which they should have, but many companies these days wouldn't have. They made the whole process easy. I will continue to buy from them with confidence.