FAN WILL NOT PHYSICALLY TURN OFF

'88 coupe - Fan will not physically turn off. Shows as 'OFF' on the climate control panel, but continues to run regardless if the car is running or turned off. Have pulled the fuse inside the passenger compartment and the relays under the hood (including the A/C relay) inside the fender mounted box. No results the fan continues to run until the negative terminal of the battery is disconnected.

The A/C relay had a discolored prong. All other relay prongs were bright and shiny - including all the fan relay prongs. Without sounding too desperate - HELP!

Thank you.

Mike

you need to replace the climate control module.meanwhile unplug the motor.i had the same problem.

The problem is likely to be a bad power module (Blower Motor Control Module). It is a common Reatta problem.

Oops! handmedown posted the answer while I was typing.

You guys are something else. I love this forum. I can now change modes from modified stationary panic to "We'll get 'er fixed on Monday."

Thank you.

Mike - '88 Black & Tan

I've got good used modules for $30 plus ship.

Jim Finn usually has them also. This is fairly common, I actually keep a spare now.

i bought a new one from carquest.

I just bought an 89 Reatta and have been surfing the forums on here for help in repairing a few issues. When I first drove the car I thought the blower motor was bad until I found that the motor had been disconnected. When I reconnected it the motor started blowing while the engine was shut off. I replaced the blower motor control module and the blower no longer runs when the engine is off. However, I cannot change the fan speed or shut it off while the ignition is on. What do you guys think the issue could be? Thanks.

Brant,

I don't know about the inability to change speeds but, I believe the fan runs all the time anytime the key is turned on.

John F.

It won't let me turn it off. When I hit the off button nothing happens.

Assuming CRT is functioning properly, fan is controlled by three items. The BCM, HVAC control module (both behind the glove box) and the blower module you replaced.

Go into diagnostics, and look at BCM Data BD20. That shows what the commanded blower voltage is. Full speed should display around 13 volts, medium around 9 or 10, and low about 5 or 6. See if that is taking place. If not, I would suspect the HVAC control module if there are no other problems going on that might call the BCM's functionality into question.

Thanks. I'll check that out.

I'm getting 14.0 v on high and 5.0 v on low. All of the other functions of the climate control seem to be working properly, I just can't change the fan speed or turn it off (until I kill the ignition).

Verify you got the proper Blower Module by checking the two connectors, 2 pins in one, 4 in the other.

If so, your HVAC Programmer is faulty, as the BCM is trying to control the blower voltage, but the programmer is not delivering the mesage to the blower.

They are no longer available new, but Rock Auto lists some rebuilt ones, and you can get used ones for less. They are not a very high failure rate part, so a used one is worth considering. Bit of a pain to R&R as you need to get to the top behind the glove box to disconnect the mix door rod and the connector, then the bottom to remove the vacuum lines. A screw holds the vacuum line plug in place, then it can be removed. Then the whole unit is held in by some screws and is really shoehorned tightly in place.

Yeah, that's the blower module I installed. Rock Auto has a climate control module listed. Is that what I'm looking for? Thanks for the help.

Yes

Two different blower models.

Bare in mind that C1 (the two pin connector) only uses one pin (of the two). There are two versions of this blower module; one with one pin, and one with two pins. Either will work in the Reatta.

I've seen both versions in Buicks and Cadillacs. Looking at schematics of both brands, I see no use for the second pin.

As for the four pin connector, only three pins are used.

I got the new climate control module today and installed it. I still have the same problem: the temperature controls work, I can change the air flow (heat, defrost, bi-level), I just can't change the fan speed or turn it off. Suggestions?

I got the new climate control module today and installed it. I still have the same problem: the temperature controls work, I can change the air flow (heat, defrost, bi-level), I just can't change the fan speed or turn it off. Suggestions?

Today you received your new "Blower Control Module", is that correct?

If you go back to post #15 you will see that if you had the correct Blower Control Module you should get a HVAC programmer.

What did you get?

No, I received the climate control module (HVAC programmer) today. I installed a blower control module previously when the blower was running while the ignition was off. Now the fan will not shut off or change speeds while the ignition is on.

I'll try that Ronnie, of course I had the battery disconnected during the install.

I tried disconnecting the both battery terminals for a few minutes but that did not fix anything. I did also check the diagnostics while the fan was set to off and got a reading of 0 volts. When I have the fan in the off position I cannot change the temperature. The CRT acts as if the fan is off even though it is still blowing. Is it possible that the new blower motor control module I installed is faulty?

Changing out the blower control module would be the easiest way to eliminate it as still being the problem. It is an expensive part to replace just for testing.

I'm looking at the service manual and a few questions come to mind:

Does diagnostics report any trouble codes?

Does the blower still run all the time even if the ignition is off?

Does the blower run anytime the ignition is on?

Does the blower always run on high speed or can you select low and the fan will slow down?

Does the fan icon on the CRT spin when you turn the fan on and stop when you turn the fan off?

What brand an part number is the blower control module?

If you have a volt meter and the time, I'm willing to help you do some testing to try and determine what is causing the problem. I'm sure other members will be willing to help as well.

In post #14, he mentions that turning the ignition off, kills the blower. That tells me it's not the blower module.

Ronnie,

There are no trouble codes.

The fan does not run when the ignition is off.

The fan always runs when the ignition is on.

The fan speed is always on high, even when I select off, low, or auto.

When I select off, the fan icon stops spinning even though the fan continues to blow on high.

I'll have to check on the brand and part #.

I picked up a volt meter today. All help is greatly appreciated. Thanks.

I think you can assume the BCM is trying to send a command to the programmer to turn off the fan since the icon changes when you make changes to the touch screen. If that is correct we need to know if the programmer is still telling the fan control module to run the fan on high OR if the fan control module is defective and keeping the fan running on high. Some testing should answer that question.

There is also the possibility that you have the wrong fan control module. If you can come up with the brand and part number we can do some checking and determine if the wrong module is the problem. I think that possibility should be eliminated before you begin testing the circuits so you know you are testing the correct parts.

Good to hear you have a voltmeter. We can do some testing as soon as we know you have the correct fan control module. In the meantime I will be thinking about the best way to test the circuits. I assume you don't have another fan control module to try on it?

To get an idea on how to test the signal sent by the programmer to the blower control module I did some testing on my car tonight. It is the test I was going to recommend to help isolate the problem with the blower running all the time. More testing may be needed. I put the method and results of my testing tonight into the form of a tutorial instead of trying to post it all here. The tutorial can be found here: HVAC Programmer Test

I did the tutorial quickly so if anyone finds problems with the tutorial or the way I tested please let me know. Questions and comments are welcomed.

Ronnie,

This is the blower control module I installed is ACDELCO Part # 1572530

Ronnie,

This is the blower control module I installed is ACDELCO Part # 1572530

Could you do the same test on your car that I did last night and report your results here? It should tell us if the programmer is sending the correct signal to the blower control module. The test can be found here: HVAC Programmer Test

If you have questions about preforming the the test feel free to ask.

I did the test, and when I turned the key to the run position and had the fan off my meter was reading 7.2 volts. Changing the fan speed to high kicked it up to about 9.2. Eventually it settled to around 8 volts and remained there through the other changes.

I did the test, and when I turned the key to the run position and had the fan off my meter was reading 7.2 volts.

This may seem to be a dumb question but was fan running when you had the connector unplugged to do the testing? I assume it was NOT running but we need to know that for sure.

From the results of your test it appears to me the programmer is telling the fan control module to run the fan even when you have the fan turned off. The question now is why.

One possibility is a bad programmer. You said in an earlier post: "I received the climate control module (HVAC programmer) today." Was the programmer rebuilt or one that is know to be good? Or was it a used one that was untested?

Another possibility is the programmer not having a good ground. Have you ever cleaned and tightened the isolated grounds near the battery? (Ground Terminals & Junction Box Location) I would want to know those grounds are good before changing any more parts.

Another possibility is you have a bad BCM OR bad wiring between the BCM and the programmer. I feel that your testing proved the blower control module isn't the problem.

If you have a programmer that is known to be in good working condition, and you know that the grounds are good, the BCM is about all that is left to try.

Eventually it settled to around 8 volts and remained there through the other changes.

If anyone has ideas on how to solve this problem please jump in.

The fan was not running during the test. Yes, I was refering to checking auto mode. The programmer I installed was rebuilt. I'll go through the ground connections and see if that corrects anything.

The fan was not running during the test. Yes, I was refering to checking auto mode. The programmer I installed was rebuilt. I'll go through the ground connections and see if that corrects anything.

The only other trouble I a having is that the instrument panel lights do not come on. I am unable to adjust the brightness of the dash/display lighting. I intend to change the twilight sensor to try and fix that. Everything else seems to be working fine.

Agree that the light problem is a separate issue and you can verify the photocell is the problem there by observing BD44 while you cover and uncover it on the dash.

You need to go back behind the glove box and get at the connector on the HVAC Programmer. Use your voltmeter to monitor the voltage on the purple and white wire on pin N. This is the signal from the BCM which should vary from 0 volts to 5 volts as you go from off, to low, to auto, to high.

Let us know what it does.

I checked my ground connections today. They were all tight and had little if any corrosion on them. I cleaned the connections and re-tightened them. I performed the test on the blower module connector again and was getting a constant 9.6 volts at all speeds - off, low, auto & high - with the ignition on. I tested the voltage on the purple and white wire of the HVAC programmer connector and was getting 5.0 volts with the ignition off. I turned the ignition on and the voltage did not change. I was unable to test at different fan speeds because I was unable to access the climate page of the CRT. Typically, when I power up the ignition the CRT wakes up on the summary page. With the HVAC programmer disconnected the CRT was waking up on the radio page and I was unable to access anything else.

You can do this reading with the connector attached to the HVAC Orogrammer as long as your one voltmeter lead can get to the purple wire from the back of the connector. You can use a pin or needle to stick down beside that wire in the connector to make it easier. Just be careful not to short other things out while your doing this. Might set it all up with the key off, then turn on the power and read it. Sure looks like the BCM is shorted out and putting 5 volts on that line all the time, which tells the HVAC Programmer to run the fan on high. Only cutting the power to the HVAC Programmer stops the fan from running.

I repeated the test with the connector connected. I'm getting a constant 5 volts; when the ignition is off, and when the ignition is on, regardless of fan speed.