AC and blower motor fan running

[cowboysteve270]

Hello Guys, I have a problem with an 88 Cadillac Deville. When I shut off the car after running it, the AC and blower motor fan continues to run after shutdown. I tried to locate the fuse for the AC, but when I pull the fuse out, 25 amp, the AC and fan blower continues to run, and the dash board lights go out. nybody ever have a problem like this? I have researched a little on it and what I found is they mention the blower control module could be bad. Is there another way I could shut it off, besides taking the battery cable off? Any help on this would be appreciated, Thank You!

[Cadillac Jim]

Some cars will let the radiator fans and the A/C run for a minute or two after shutting off the car. If it's just staying on, there are likely several fuses involved and you would need someone with a model year 1988 FSM to get the list, but the real problem is to find the short and fix it.

As a general thing, I would start with the wire at the connector to the fan motor and make sure that it was OK and all its connections were good, then work along the wiring harness to the first point where a cable goes through the firewall. Many wiring harnesses use a connector there; if so, it should be checked. If it's a feed-through, check for damaged wires. On the other side under the dash, start with the wires from the A/C and heater controls. They probably go to a module under the dash.

If it's not that simple, you will need a way to do diagnosis on the 1988 model year. I believe that you can get the OBD I codes from the car without a code reader but I don't know how. The procedures posted on Caddyinfo start at model year 1989 but may work for your car:

http://www.caddyinfo.com/readingcodes.html

[Cadillac Jim]

Hello Cadillac Jim...Thanks for answering my posts..Yeah, its not the electric fan by the radiator, its the blower for inside vehicle. The blower continues to run, along with the AC pumping out cold air. What happen was we had some heavy rain storms on the East Coast, and after that, the blower and AC continues to run after shutoff. I was trying to pull the fuse to shutoff the AC compressor and blower, but nos such luck.

I understand that. But there are options in the car's setup to allow either or both of these to run after the key is off. But without the compressor, the A/C blower won't be doing much and I have never seen that set to run after the key is turned off, so I don't know how long it would run. But I would bet that it is a minute or less.

The radiator fans can even come on with the key off if the engine coolant temperature exceeds a given threshold (I think something like 240 F but I don't recall), which is unlikely if it wasn't reading that hot when the key was turned off but is possible, and does happen.

The A/C compressor rarely shares a fuse with the blower motor. The fuse you pulled was probably for the console with the A/C switches and buttons, which was the same fuse as the instrument panel. The blower motor probably has its own fuse.

The only FSM material I have on hand is the 1997 model year (good for 1996-2002 Eldorado, 1996-1998 Seville/Deville, limited use 1992-1995 Eldorado/Seville/Deville) and a 2011 DVD, good for everything 2002-2011.

In the 1997 FSM, the blower motor has three wires: power through the 50 Amp INDVERT fuse, which also powers the inavertent timed power that stays on for ten minutes after the key is off or until you open a door, whichever comes first. But the heater and A/C blower motor always has power. There is a ground, then there is a GRY wire that goes to the heater and A/C programmer, which is under the dash and takes its orders from the IPC or climate control panel over the car's network. If the GRY wire gets grounded, you can't turn off the A/C blower except by pulling the 50 Amp INDVERT fuse, which turns off a lot of other things like the radio.

But usually a blower motor that won't turn on or off has bad internal electronics and must be changed. But I don't know whether or not any of what I see in the 1997 model year applies to the 1988 model year.

[barczy01]

You need a power module for the blower motor. It sits in the HVAC case on the firewall with two connectors in it. GM# 16061602

[Logan]

That is a known failure mode for the blower control module for Cadillacs of that era. HVAC blower stays on..

[cowboysteve270]

Hello Cadillac Jim...Thanks for answering my posts..Yeah, its not the electric fan by the radiator, its the blower for inside vehicle. The blower continues to run, along with the AC pumping out cold air. What happen was we had some heavy rain storms on the East Coast, and after that, the blower and AC continues to run after shutoff. I was trying to pull the fuse to shutoff the AC compressor and blower, but nos such luck.

I understand that. But there are options in the car's setup to allow either or both of these to run after the key is off. But without the compressor, the A/C blower won't be doing much and I have never seen that set to run after the key is turned off, so I don't know how long it would run. But I would bet that it is a minute or less.

The radiator fans can even come on with the key off if the engine coolant temperature exceeds a given threshold (I think something like 240 F but I don't recall), which is unlikely if it wasn't reading that hot when the key was turned off but is possible, and does happen.

The A/C compressor rarely shares a fuse with the blower motor. The fuse you pulled was probably for the console with the A/C switches and buttons, which was the same fuse as the instrument panel. The blower motor probably has its own fuse.

The only FSM material I have on hand is the 1997 model year (good for 1996-2002 Eldorado, 1996-1998 Seville/Deville, limited use 1992-1995 Eldorado/Seville/Deville) and a 2011 DVD, good for everything 2002-2011.

In the 1997 FSM, the blower motor has three wires: power through the 50 Amp INDVERT fuse, which also powers the inavertent timed power that stays on for ten minutes after the key is off or until you open a door, whichever comes first. But the heater and A/C blower motor always has power. There is a ground, then there is a GRY wire that goes to the heater and A/C programmer, which is under the dash and takes its orders from the IPC or climate control panel over the car's network. If the GRY wire gets grounded, you can't turn off the A/C blower except by pulling the 50 Amp INDVERT fuse, which turns off a lot of other things like the radio.

But usually a blower motor that won't turn on or off has bad internal electronics and must be changed. But I don't know whether or not any of what I see in the 1997 model year applies to the 1988 model year.

Thanks Cadillac Jim....Yeah, I am going to have to take the car in and see whats up with the problem. I heard it could be a few things, like what you said a possible ground wire short and blower motor failure, on and off switch, blower motor control module, etc. I will see what they have to say and I will report back to you on this topic. Thanks for your help!

[cowboysteve270]

You need a power module for the blower motor. It sits in the HVAC case on the firewall with two connectors in it. GM# 16061602

Thanks! I am going to look up that GM part.

[cowboysteve270]

That is a known failure mode for the blower control module for Cadillacs of that era. HVAC blower stays on..

So, its a common problem for these years in the caddy deville? I am going to take the car to the shop, so they could at least tell me exactly what it is. If it is easy to change, I will do it myself, but I have to know what I need to change. Thanks for the help!

[barczy01]

Its a common problem. Its 2 7mm screws quite easy to do.

[Logan]

Barczy and me are posting at the same time....different names for the same module... common...no code failure...blower stays on.

Don't think you need a shop. Easy to do.

This is from a Allante posting...but it does have a picture. #1 is the problem. Yours will be similar.

http://www.justanswer.com/cadillac/5kiz9-cadillac-allante-1988-allante-not.html

[cowboysteve270]

Barczy and me are posting at the same time....different names for the same module... common...no code failure...blower stays on.

Don't think you need a shop. Easy to do.

This is from a Allante posting...but it does have a picture. #1 is the problem. Yours will be similar.

http://www.justanswer.com/cadillac/5kiz9-cadillac-allante-1988-allante-not.html

I appreciate and Thank You guys for helping me out. OK, let me get this straight, this part is in the back of my glove box where the fan is, right? So, I have to basically take the glove box off to get to the blower, or the panel underneath the glove box, is that correct? If it is, than I believe, judging by the picture #1, that the power module sits on top and I should be able to see it. Is that right? I found a video on You Tube for a 96-99 caddy deville,

How To Replace Install AC Heater Air Temperature Control Cadillac Deville 96-99 1AAuto.com,https://www.youtube.com/watch?v=9qpog4AYb_Q, is that correct for changing the module?

[cowboysteve270]

Its a common problem. Its 2 7mm screws quite easy to do.

I found a video on You Tube for a 96-99 caddy deville,

How To Replace Install AC Heater Air Temperature Control Cadillac Deville 96-99 1AAuto.com,https://www.youtube.com/watch?v=9qpog4AYb_Q, is that correct for changing the module? Thanks, barczy01!

[Logan]

That is not the correct part.

See #7 in picture: http://www.justanswer.com/cadillac/3qb4w-deville-hvac-high-speed-the-relay-location-diagnostic-info.html

[cowboysteve270]

That is not the correct part.

See #7 in picture: http://www.justanswer.com/cadillac/3qb4w-deville-hvac-high-speed-the-relay-location-diagnostic-info.html

OK, got it...The Power Module is located under the hood in the blower housing.

From the picture, it looks like it is pretty easy to get to and to check the voltage to see if it is bad. Thanks for all your help, Logan!