1997 Cadillac Deville heating problems

[SARAH313]

I have a 1997 Deville with no heat right now. I don't have much money to put into this so hopefully its a quick easy fix.

First off I am getting 4 current codes :

ACM B1315

SDM B1136

TCS C1233

MMM B1249

Ok The heat doesn't blow out or cold for that matter. But if you move the temperature up or down you can feel the difference in temperature. I was told the blend doors are opening and closing. I was also told the blower runs hot even though the key is not in the ignition.

Also the DIC always says check coolant level although it is full.

1 last thing although I doubt this matters, apparently the A/C compressor is missing, must have been in an accident and was never replaced. I just want to make sure this doesn't affect the heat.

Please someone give me advice on what this could be, we are getting snow now and I have no heat or defrost to be able to drive.

Thanks

[rockfangd]

my first guess would be a faulty blower motor. I dread them because of where they are located, dd it just quit altogether or does it sometimes work? have you checked any fuses or relays?

[SARAH313]

Yes it is dead altogether. We also checked all fuses.

[Ranger]

Your blower motor has moved to the great beyond.

[SARAH313]

I ordered the blower motor and blower motor resistor. I was wondering where the rsistor is and is there anyone who may have a diagram of the location.

[Ranger]

There is no resistor. Blower speed is controlled by PWM voltage to the blower. The blower is on the firewall. Here is a post I made on another site on how I did it on my (previous) '97 Deville while it was still fresh in my memory.

Remove the rear plug wires. Remove the ICM and set off out of the way. FYI, there are two hidden mounting bolts on the back of the ICM that require the Braille method to remove (don't drop 'em. They will fall into the cradle and are darn near impossible to find. Don't ask) Unclip the EVAP solenoid from the rear cam cover and move it out of the way. Open the hold down clip on the loom running along the rear cam cover. Once you have everything cleared out of the way, unplug the blower motor. Now remove the three bolts in the center of it. that will allow you to remove the inertial plate. That is the large black disc in the center. Once that is out, the armature will come out and then the 5 bolts around the perimeter (some of which need to be done by the Braille method with a 1/4" drive socket. That's the easy part. The new one has been redesigned and has to go in in one piece. You'll notice, it won't fit. There is not enough clearance between the rear cam cover and the firewall. Remove both torque struts (dog bones) and replace the left one (longer of the two) with a small (7") turnbuckle. Tighten up on the turn buckle and you should be able to rock the engine forward about an inch or so. That will give you just enough clearance to get it in but do not expect it to go without a fight. Now fight with that snake of a wire loom and pull it up enough so that you can get the blower somewhat into position with the loom behind the back end of the blower motor so as not to be in the way. Now wiggle, push, turn and curse the blower motor till it pops into place. You will need to use a little force and the cage as well as the housing will give a little so that is not a problem. Once it pops into place let out a loud YYYES. Once again use the Braille method to replace the lower of the three mounting bolts. Yes I said three. The new motor as I said is redesigned and only uses three. Don't forget to put the heat shield in place first or you'll have to take it apart and do it all over again. Don't ask me how I know. Now simply put everything back in place, remove the turnbuckle and replace the torque struts, wipe up the blood and finally clean and bandage your wounds. Now sit down and

The first time took me about 3 hrs. I did not rock the engine forward. I used a pry bar and forced it in place on the advice of a Cadillac mechanic. Big mistake. I obviously cracked the cage. It lasted 7 months and exploded about 2-3 weeks ago. I got it warrantied and this time I knocked it out in about half the time or better.

Good luck.

[BocaBob]

I have a couple of questions...

1.) Why do part stores sell a blower resistor for the 97 DeVille is the car does not have one??? I was told it was located behind the blower cage. I bought one but waiting to install when the new blower comes in.

2.) Cadillac parts lists a blower module instead of a resistor for $1200.00...for this model.

My daughter Sarah (on original post)is saying that one lead on the blower harness plug is HOT all the time... even with the ignition off. Wouldn't that burn any blower. Doesn't that show signs that the blower module is bad???

[BocaBob]

Hey RANGER,

Is the PWM the blower module that Cadillac parts sells for $1200.00???

[BocaBob]

WE had a new blower plugged in before installation but the blower did not move with the ignition on... It was new in the box but we sent it back.

WE were told the engine has to be running for the blower to start... Is that true?

[KHE]

The blower motor harness has three wires - one is battery voltage, one is ground and the third is the signal wire that comes from the ACM to control the blower speed.

The blower motor will not run until the engine coolant temperatire is above a certain temp. That is so the system will not blow cold air.

Be sure to buy the foil/fiberglass heat shield that goes over the motor. It used to come with the blower but now it must be purchased separately.

[BodybyFisher]

That is true, the blower will not run until about 120 degrees, that is to stop from freezing up the windshield and occupants with cold air, when it comes on, at 120 degrees it is ready to deliver warm air and begin defrosting the windshield

What happens to the motor is that the ignition wires lean up against the controller on the back of the motor and EMF damages the components, ignition wires must be kept away from the motor's controller. The foil controller cover that Kevin is referring to helps to shunt that EMF to ground

It may not be EMF but high voltage leakage the more that I think about it, if you have ever seen older wires flash in the dark and the tell tale burns on them, that is enough to damage sensitive electrical components

[Ranger]

Hey RANGER,

Is the PWM the blower module that Cadillac parts sells for $1200.00???

PWM means Pulse Width Modulation. It is like turning a fan switch on and off. Longer on times equal faster speeds. When I replaced my blower motor I think I paid something like $200 from Rockauto. I'm not sure what "blower resistor" they are selling. I'm lost there.

[BocaBob]

Hey RANGER,

Is the PWM the blower module that Cadillac parts sells for $1200.00???

PWM means Pulse Width Modulation. It is like turning a fan switch on and off. Longer on times equal faster speeds. When I replaced my blower motor I think I paid something like $200 from Rockauto. I'm not sure what "blower resistor" they are selling. I'm lost there.

RANGER DANGER!!! I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille. OH... Rockauto has a Heater/AC Control Module $700 - $900... (not the Control HEAD)

DANGER IDIOT!!! Your detailed info on removing the blower above proves that your are indeed an IDIOT. The casing has a flat spot and if you turn the flat spot downward, the blower removes easier halfway through your removal process.

RANGER LOST!!! Stay lost and off this BLOG because people are serious here and in need of correct info. Previous Cadillac dealer wrenches only!

[BodybyFisher]

Hey RANGER,

Is the PWM the blower module that Cadillac parts sells for $1200.00???

PWM means Pulse Width Modulation. It is like turning a fan switch on and off. Longer on times equal faster speeds. When I replaced my blower motor I think I paid something like $200 from Rockauto. I'm not sure what "blower resistor" they are selling. I'm lost there.

RANGER DANGER!!! I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille. OH... Rockauto has a Heater/AC Control Module $700 - $900... (not the Control HEAD)

DANGER IDIOT!!! Your detailed info on removing the blower above proves that your are indeed an IDIOT. The casing has a flat spot and if you turn the flat spot downward, the blower removes easier halfway through your removal process.

RANGER LOST!!! Stay lost and off this BLOG because people are serious here and in need of correct info. Previous Cadillac dealer wrenches only!

Whoa Bob, who the hell are you? PWM stands for Pulsed Width Modulation. Pulse width modulation is not something that you BUY and Ranger did not suggest that you go out and BUY PWM. Its a TECHNIQUE NOT a DEVICE.

Pulse-width modulation (PWM) is a commonly used technique for controlling power to inertial electrical devices, made practical by modern electronic power switches

There is no blower motor resistor in a cadillac, I have one in my Monte Carlo and as a matter of fact I am going to buy one now for it.

We NEVER need to replace the control module, the motor is problematic and needs replacing its a common repair. Not saying that your control module does not need replacing from someone trying to diagnose your problem and blowing it.

That FLAT spot you are talking about?, yea great, typically cutting of the cover and tilting the engine is required to get a blower motor out, it even has CUT HERE on the cover.

This is your FOURTH posting here, if you EVER post a nasty post like this again, you WILL be banned immediately, RANGER is one of our most knowledgable long term members who had a close relationship with the guru and he carries a lot of the guru's legacy.

YOU sir misunderstood what RANGER said, he did NOT SAY go out and buy a PWM as you tried to do, now that is funny! Read up on PWM

http://en.wikipedia....idth_modulation

[BocaBob]

Hey RANGER,

Is the PWM the blower module that Cadillac parts sells for $1200.00???

PWM means Pulse Width Modulation. It is like turning a fan switch on and off. Longer on times equal faster speeds. When I replaced my blower motor I think I paid something like $200 from Rockauto. I'm not sure what "blower resistor" they are selling. I'm lost there.

RANGER DANGER!!! I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille. OH... Rockauto has a Heater/AC Control Module $700 - $900... (not the Control HEAD)

DANGER IDIOT!!! Your detailed info on removing the blower above proves that your are indeed an IDIOT. The casing has a flat spot and if you turn the flat spot downward, the blower removes easier halfway through your removal process.

RANGER LOST!!! Stay lost and off this BLOG because people are serious here and in need of correct info. Previous Cadillac dealer wrenches only!

Whoa Bob, who the hell are you? PWM stands for Pulsed Width Modulation. Pulse width modulation is not something that you BUY and Ranger did not suggest that you go out and BUY PWM. Its a TECHNIQUE NOT a DEVICE.

Pulse-width modulation (PWM) is a commonly used technique for controlling power to inertial electrical devices, made practical by modern electronic power switches

There is no blower motor resistor in a cadillac, I have one in my Monte Carlo and as a matter of fact I am going to buy one now for it.

We NEVER need to replace the control module, the motor is problematic and needs replacing its a common repair. Not saying that your control module does not need replacing from someone trying to diagnose your problem and blowing it.

That FLAT spot you are talking about?, yea great, typically cutting of the cover and tilting the engine is required to get a blower motor out, it even has CUT HERE on the cover.

This is your FOURTH posting here, if you EVER post a nasty post like this again, you WILL be banned immediately, RANGER is one of our most knowledgable long term members who had a close relationship with the guru and he carries a lot of the guru's legacy.

YOU sir misunderstood what RANGER said, he did NOT SAY go out and buy a PWM as you tried to do, now that is funny! Read up on PWM

http://en.wikipedia....idth_modulation

HOW DO I KNOW YOU DON'T KNOW WHAT IS GOING ON WITH THE CADILLAC??? YOU USE WIKI... LOL

WHO ARE YOU... after your post everyone can answer that...

I know what voltage modulation is and have even measured it on an oscilloscope. RANGER said "It is like turning a fan switch on and off." Swithes can change voltage... Learning something here FISHER BOY???

Voltage signal would indicate that the blower motor is bad. If you get no voltage then the programmer module is bad...

Thanks for the laughs... I rarely have time to match wits with someone with so so very little.

[BodybyFisher]

Listen, it was YOU who said this:

I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille

and this

Is the PWM the blower module that Cadillac parts sells for $1200.00???

Those statements to me are indicative of someone who does not understand what PWM is. As far as WIKI goes, since you stated what you stated above showing you didnt understand, and since I dont have time to sit here and write a description of PWM, I googled PWM so that I could get a quick description of it for you.

Now, I am not sure what your problem is, why you are here or if you are here to start trouble or what, but I would appreciate it if you would chill out. We actually attempted to help you and your attitude is inappropriate

[BodybyFisher]

If you were so knowledgable, to be able to measure the PWM with a scope, why did you call rockauto and ask that question? Can you explain that?

[Ranger]

I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille

"Tis far better to remain silent and let people think you are a fool than to speak up and remove all doubt."

[hjb981]

I was a bit shocked reading this thread. BocaBob - please understand that all the people who try to answer your questions are actually trying to help you. If you follow someones procedure and think that you have found a better way, how about saying "thanks for the tips, I tried it and think there is an easier way of doing it: ..." instead of calling the other person an idiot? Ranger has been on this forum for many years, helping people like you and I without getting any compensation for it - he even pays to keep this site running (he is a supporter, as is BodybyFisher).

Sure, it would be nice with a site full of Cadillac Mechanics solving problems for free, but most people willing to take the time to do this are enthusiasts. Many of those enthusiasts have done a lot of work themselves, and together have quite a bit of valuable knowledge. If only Cadillac Mechanics were allowed to answer, we would have very few answers here.

BodybyFisher tried to explain PWM so that no-one would think that it is a device. He was doing this to avoid any misunderstandings. It is not easy to judge another persons knowledge on a forum like this one, and therefore sometimes people end up explaining something that the other person already knew. You state that you have measured voltage modulation (not the same as PWM) with an oscilloscope, and that switches can change voltage. When I read that, I get the idea that "maybe this person is confusing voltage modulation with pulse modulation". Then I am inclined to post a reply and clarify it. I am not doing that to try to "match wits". Not at all! I am only trying to help! If you already knew this, then what is the problem? No harm done! Anyways, here goes:

In pulse width modulation, the voltage does not have to change. The "switch" can very quickly turn on-off-on-off-on-off and so on with just one voltage. In other words, the voltage supplied to the fan would be 12-0-12-0-12-0 and so on. If it for example stays at 12 V for 5 ms, and then 0 V for 1 ms, the fan would run quite fast. If it stayed at 12 V for 1 ms and 0 V for 5 ms, the fan would turn rather slowly. Since the pulses are so short (ms means millisecond - there are 1000 ms for each second), the fan speed will not go up or down very much with each on or off cycle, but keep a steady mean value. The pulse lengths are only examples to explain the principle - I do not know the actual pulse lengths in Cadillac HVAC (heating ventilation air conditioning) systems. Please do not feel offended because you may be able to find this information on Wikipedia. Even if you understand this already, there may still be someone else searching and reading this forum later, who will find this useful.

Another thing that I thought of: instead of waiting for the engine to reach 120F, just put the fan on Hi (press the button twice to get to Hi, not Auto Hi). You could also try alternating between Hi and completely turning the system off, with the Off button, to see if there are any changes on the output. If you have an oscilloscope to check this, great! Then you should be able to see if the pulse widths are changing or not. Yes, this is a very simple thing, and maybe so obvious that everyone thought of it but no-one mentioned it. I am only writing this because I want to help and I believe that it may be useful to someone.

One comment to Sarah, who posted the codes: did you also have any history codes? They may also be helpful in finding any problems.

It is also important to remember that even a Cadillac Mechanic could not accurately answer all questions on an Internet forum. Diagnosis is much harder for any mechanic if he/she cannot examine the car. When I use this forum, I usually get several ideas on what to look for or what to do. Then I try and sometimes I find a solution. Sometimes I don't. I am still grateful to the people who took their time trying to help me.

[BodybyFisher]

Thank You hjb981

[genesis2011]

Thank You hjb981

Hello Sir I really need your help. I have a 1999 deville with no heat. I am getting b1340 and b1341 codes which show air mix movement fault doors 1and2. Do I need to replace the actuator for the pax and driver side controls? Or am I to be looking at the doors? I have a diagram which appears to be of the entire blower motor and shows the driver side actuator on the bottom and the pax side on top. Also CAN I get to all this from the removal of the glove box. Confused and need help. Any help u could give would be greatly appreciated. Thank you

[airmike]

I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille

"Tis far better to remain silent and let people think you are a fool than to speak up and remove all doubt."

Are we having a full moon or something? What is up with all the negative post lately?

hjb981-awesome post

[Ranger]

I called Rockauto and while laughing... they said they have no PWM for the 97 DeVille

"Tis far better to remain silent and let people think you are a fool than to speak up and remove all doubt."

Are we having a full moon or something? What is up with all the negative post lately?

hjb981-awesome post

Did you read what prompted that post?