ntmyzr1

I had my 1990 ZR-1 out for a ride today and noticed the heater/ac fan control would not turn the fan down to low speed (1). It did seem to reduce the fan speed from 10, but not past about 6 or so. Then, when I shut off the engine and took the ignition key out, the fan continued to run. Since I have a battery cut-off switch, I disconnected and then reconnected the battery to see if it would resolve the problem. It did not.

About 10 years ago, my heater temperature control switch stopped working, and I had that entire unit rebuilt by Chevy. I would guess my problem is back in that control unit. However, when the ignition is off, I would expect the fan to stop running even if I can't control the speed.

Any ideas?

Thanks

WVZR-1

It certainly sounds like a Blower Control Module will fix your fan issue. It is likely the fix on 99 out of 100. It's one of the more accessible parts you'll ever have to deal with the service of. Top of the evaporator/blower module under the hood. It's good that you have the battery disconnect but if not you would only need to unplug the unit.

It should appear very similar to this image:

ntmyzr1

Thank you WV; I appreciate your advice. Is there any way I can check the Blower Control Module, or should I just get a replacement?

WVZR-1

If you've done nothing recently except drive it and shut it off then the Blower Control Module is likely a sure fix. If you've been doing extensive maintenance or any diagnostics that involved wiring then you need to maybe troubleshoot the issue. The module is similar to most C68 through out the GM car line of the times and it's generally considered the fix!

I'm sure there should be diagnostics in the FSM.

ntmyzr1

Thanks again WV. I'll pick up a new module and put it in.

RICHARD TILL

Several years ago my 1990 did the same exact thing as yours. A blower Control Module fixed it.

ntmyzr1

I've ordered this part through Amazon twice, but both were wrong. I hate to Pay $250 to Chevy. Does anyone have a reliable source for the Blower Control Module? Or have one for sale?

Thanks

WVZR-1

What part number did you buy from Amazon? Did it just have maybe 1 extra pin? Where are you located?

ntmyzr1

I ordered AC Delco 15-71642. Altho that part number was on the box, it was not the part in the box. From looking on-line, I believe they sent me a 15-71971. It was too long to fit in the air box and had the 2 pin and 4 pin connectors reversed.

WVZR-1

By part number the one you ordered is correct and it's from Amazon directly it appears. I can't imagine Amazon doing those direct so I'd guess it's some overstock that was part of a buy-out and some mis-boxed material was included. They've only one left so you've got a last effort with them I'd guess and then it's time to do something else.

Looking at the price you paid you've no choice but to give it the last effort from them.

Where are you located?

After receiving two mis-packaged parts is it likely that maybe Amazon would send one from one of the other "sellers" they refer to and absorb the difference? Don't know but it might worth the ask!

speedycat3

I just got mine replaced after suffering the same problem and ordering the correct oart number 15-71970 , from Amazon.
I received an AC Delco part that was slightly different in the electronic part, and the conecctors were reversed.
I had two choices, disassemble my existing one and using the backing plate from my old one so that it would face the right way (not that there was any interference installed reversed) or install it with the plugs reversed and plan accordingly.
After making sure that it all fitted the way it should and there was no contact with anything else inside, I installed the new part, plugged the in and reconnected the battery.
All good in the AC controlls and no more blower blowing all the time.
I must say that there is an awful lot of room for a longer part in my 1993,
When you take out the old part, make sure to only take off the 3 bigger screws that hold the supporting plate to the case, and not the 2 smaller inner screws that support the resistor to the backing plate. If the resistor is disassempled and ends up inside the heater box, then you could face a problem of the new part not fitting inside.
I realize that your is a 90 ZR1 and mine is a base 1993, but I thought the information might help you out.

WVZR-1

'90 - '92 use one and '93+ use a different one - similar parts but different.

ntmyzr1

Thanks guys. I have a '90, and the part is too long to fit in the heater box. I am in the Chicago area (car is in the Sturgeon Bay, WI area). I'm not very optimistic about Amazon, but I'll take a look at the other suppliers as you suggest and then give them a call. Any suggestions on another vendor? I see the part on some AC Delco supplier, but I've never heard of them so am reluctant to deal with them.

ntmyzr1

I ordered and received another part from Undercar Parts through Amazon. It was also the wrong part. All 3 parts came in a box with an A C Delco label with the correct part number on the label, but the same wrong part in the box. As I examine the new part, it doesn't have any A C Delco markings on it like my original. I'm thinking all the vendors are getting this aftermarket POS from China.

I think I'll have to bite the bullet and go to Chevy.

xlr8nflorida

Maybe look on Ebay to see if you find what you are looking for.

More expensive than Amazon but cheaper than what you quoted from dealer.

http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40