87 Cadillac Brougham Climate Control Problem

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  #1  
Old 12-01-09, 04:04 PM
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87 Cadillac Brougham Climate Control Problem

Hi, Have a 1987 Cadillac Brougham rear-wheel-drive. When "auto" pushed on the in-dash Electronic Climate Control unit, blower does not come on regardless of temperature set. But, sometimes blower just starts as I'm driving along, skips-off for a second and then stays on. When car turned off, same problem upon restart. Was able for a while to push the defrost button, blower would come on and then push the auto button to keep it on. Now the defrost button will not start the blower when pushed. But occassionally the same thing in defrost--blower just starts-up and runs until vehicle turned-off.
Bought a "new" in-dash Electronic Climate Contol unit. That did not fix the problem. Same problem in auto or defrost mode.
Wires to/from ECC unit look just fine. Don't see how there could be a short in the wiring--no movement of any sought in the area--but I guess anything is possible.
Can the blower per se get a short? With the fact that the blower works when it wants to, did not think it was blower.
Stumped and any help appreciated.

Thanx

Bill
 
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  #2  
Old 12-03-09, 09:27 PM
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did you check the blower motor? i believe they have power to the motor all the time and use the ecc to control the ground to vary the speeds. could be a bad blower motor or gm had a problem with the power connectors melting to the blowers(not the one at the motor, down the line a bit)
 
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Old 12-03-09, 11:38 PM
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Seen this on other models of Caddys check the blower motor relay in the power box under the hood against the fire wall my laptop with alldata on it is at my shop right now and cant for the life of me remember my password to access it from my home pc.
Since you didn't mention a check engine light (yes the ECU does monitor the auto climate control) I don't think its the sun load sensor but if you do it could give you a direction to go also.If the relay is good like the other post said there is an always hot
connection to this relay and it gets its signal from the dash control unit it relies on three sensors a cabin temp the sun load sensor and an outlet temp sensor to adjust the fan and blend doors for desired temp in the car. Any of these should throw a check engine light if bad. The relay or plug is your most likely cause with a motor ground being the next if those check out.
 
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Old 12-04-09, 06:52 PM
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maniac mechanic this caddy doesn't use a relay.it has power to the blower and ecc (elect climate control) power module direct from the battery through a fuse link. the ecc power module uses the ground to control blower speeds. since he has had the blower start and stop while driving it could be a bad blower.he should check for power and ground at the blower(use a meter to see 12volts), if it has both replace the blower. if not trace back the problem circuit.
i don't think you would get a check engine light for a climate control problem. i would copy the wiring diagram, but i don't know how to put an image in this post.
 
  #5  
Old 12-05-09, 05:00 PM
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Thank You: mech 1 & Maniac Mechanic

Many thanks for you help. I have the Service Manual. Pretty sure it has the wiring diagrams. Have to become more adept at following them.

Thanks, Merry Christmas and Happy New Year

Bill
 
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