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Coolant temperature light comes on

Tiny
MORRIFIC
  • MEMBER
  • 1992 CADILLAC DEVILLE
  • 5.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 198,000 MILES
Radiator was change and seems the thermostat is not working properly as there is practically no heat in the car.
Wednesday, March 28th, 2018 AT 1:05 PM

47 Replies

Tiny
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Good afternoon.

Was the heat working prior to the radiator repair?

Roy
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Wednesday, March 28th, 2018 AT 2:26 PM
Tiny
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No, it was not.
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Wednesday, March 28th, 2018 AT 2:54 PM
Tiny
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Okay with the Cadillac's there is a programmer that controls the movement of the blend door to glove heat and AC. When you switch from AC to heat, can you hear the mode door moving?

Roy
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Wednesday, March 28th, 2018 AT 3:02 PM
Tiny
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Hi Roy, this is the wife's car and she said sometimes it stalls on a red light or a stop, but starts right away.
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Wednesday, March 28th, 2018 AT 3:03 PM
Tiny
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Okay, that is a different issue. It has nothing to do with the heat.

The old Cadillac's have an idle control motor on the throttle body that fails and causes this exact issue. You can check it by going under the hood and seeing if it fully extends with the key on before you crank it.

Roy
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Wednesday, March 28th, 2018 AT 3:06 PM
Tiny
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Roy, the compressor for the AC has not been working for years. She said since the radiator was replace the light comes on and even before the replacement it was coming on a few occasion. She believes that was only when the coolant was low.
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Wednesday, March 28th, 2018 AT 3:11 PM
Tiny
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Okay, that is because there is a low coolant switch in the radiator to warn you when the coolant level is low.

Pnce you fill it, it may be air bound. Try removing the radiator cap and running the engine about 1200 rpm. Have someone watch the coolant level and keep it full. That will force the air out of the system. If the air is the issue, you will get heat.

Beyond that it could be either the heater core being clogged or the programmer not working correctly.

Roy
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Wednesday, March 28th, 2018 AT 3:21 PM
Tiny
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Roy, until what time are you working as it seems to me that you are on the west coast as I am on the east coast? As for the radiator, do you not think that they will have done everything accordingly before giving the car back, unless they were not that qualified.
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Wednesday, March 28th, 2018 AT 3:40 PM
Tiny
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I am in central PA.

You would think so. A lot of shops are not as familiar with the old Cadillac's auto climate control systems. They are totally different than today's systems.

I will be on for about another hour.

Roy
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Wednesday, March 28th, 2018 AT 3:47 PM
Tiny
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Good to know as I will take the car for a ride and will get back to you tomorrow. Have a good evening.
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Wednesday, March 28th, 2018 AT 4:01 PM
Tiny
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You as well.

Roy
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Wednesday, March 28th, 2018 AT 4:04 PM
Tiny
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Hi Roy, you where spotted on for the heat as I did just like you said and it works well. Last night when I took the car for few errands it seems that the car was going to stall several times and it backfire just like if the mixture of air/gas was not properly adjusted. My belief was that there was a lot of humidity or condensation in the tank since she runs low on gas. What is your take on this?
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Thursday, March 29th, 2018 AT 1:19 PM
Tiny
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Okay.

No, I do not believer it is bad fuel. I would have the plugs checked, timing checked and also that idle control motor checked. The distributor cap and rotor should also be checked for carbon tracking.

Roy
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Thursday, March 29th, 2018 AT 1:22 PM
Tiny
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Anyway I added a deicer to the gas tank and looks like it is okay. A lot of white smoke comes out of the tail pipe, why? Also, are you good with the with all the new technology of today's car as I have a problem with my car, Chrysler 300, 2011.
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Thursday, March 29th, 2018 AT 1:43 PM
Tiny
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White smoke concerns me. It is an indication of burning coolant.

You have a all aluminum engine that had a history of head gasket failure and intake manifold gaskets leaking causing this white smoke. It needs to be checked to confirm.

Yes I am up on the new stuff.

Roy
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Thursday, March 29th, 2018 AT 1:46 PM
Tiny
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Roy : Thanks for the infos for the caddy. Now for the Chrysler 300-2011, I put a car battery 3 weeks ago and prior to that I had changed a relay ; this morning the car would not start at all plus the fob key was not detected and there was no power at all, could not even unlock doors and trunk., Battery for fob were changed approximately 3 months ago. Boosted the car but I suspect there is something draining the car battery.
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Thursday, March 29th, 2018 AT 3:04 PM
Tiny
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Ok, The first thing I would do is to charge that battery. Charge it until it is 12.6 volts. That is a full charge

then you need to check the charging system. With the engine running it should be 14 to 14.5 volts

once you get the battery charged, the key fob should work. Right now you have low voltage and nothing will work

Roy
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Thursday, March 29th, 2018 AT 3:20 PM
Tiny
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Roy: forgot to tell you that was the only thing that I've changed so far besides the regular maintenance. Just by driving the car, how long would it take to have it charged to 12.6 v
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Thursday, March 29th, 2018 AT 3:39 PM
Tiny
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Use a battery charger. If you have a charging issue, it will not charge. Also, the alternator is for maintaining the battery not for charging it.

Roy
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Thursday, March 29th, 2018 AT 3:43 PM
Tiny
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O.K. Roy, I will charge the battery and get back with you tomorrow, have a good evening.
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Thursday, March 29th, 2018 AT 4:02 PM

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