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Discussion Starter #1
Hey folks, new to this forum and in need of some assistance (a lot of assistance my wife says, but that's for a different forum I'm sure!). I have a '96 DeVille with about 105K miles on it. I dig it (of course), but when the weather turned chilly a few weeks ago I dialed in the temp to something more suitable than the 45 my outside temp was reading. To get to the point: my heater didn't heat anything. Regardless of what temp I set it only blows cold air. I checked the fuses (on the back of the rear seats from the trunk) and there was no fuse labled heater, but all of the fuses there checked out OK. Is there a fuse block under the hood? Is there a fuse for the heater? Am I looking at huge dough to heat myself up? Thanks a TON for any assistance you may be. Take care.

K.
 

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2016 XTS FWD Platinum
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There is no specific fuse for your heater as the heating system is not electric per se. You have one of two problems. There is a little vacuum operated door that allows either heated or cooled air to enter into the passenger compartment. The door may be stuck in the full cold mode or possibly the linkage that controls it may have become disconnected. It is below and behind the glove compartment. Usually removing the glove compartment and the lower dash allows easy access to it. The other problem could be with your cooling system. Check your coolant level to make sure that nothing is leaking. If you are low on coolant, it will affect your heating system.

Max
 

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2005 CTS-V, 1994 Infiniti Q45
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Your heater core could also be messed up.......

The heating system works by recirculating engine coolant through a radiator looking device and the fan blows air over it........

If its not what max mentioned, Id say its either the heater core itself, or the little valve that regulates the amount of coolant flow into the core......

If you were low on coolant (enough to make the heater not work), you would have a LOW COOLANT message, possibly overheating, and maybe some noise from the water pump cavitating........

Welcome to CF..... Thanks for signing up :wave:
 

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I don't think the later models have a valve regulating coolant flow to the heater core. I could be wrong, but I think coolant flow to the core is continuous unless it is leaking.

Max
 

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2005 CTS-V, 1994 Infiniti Q45
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Oh...... Maybe so..... Most cars work the way I described......

Then how does it work..... Is there a seperate compartment for the evaporator then???
 

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Discussion Starter #6
Thanks a boat load for the ideas. They have given me some things to check-out. If I ever figure out what it was/is I will be sure to let you know! Thanks again and keep it up.

K.
 

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Elwesso--Modern Cadillacs (I don't know about other brands) don't utilize the hot water valve shut-off anymore. I remember my 75 Cadillac had one but they quit using them in the 80's or 90's. Now, when air enters into the evaperator/heater case, the air is cooled when it goes through the evaperator (if the A/C is on) and then if directed, will go through the heater core to heat the air. If full heat is desired, all air will pass through the heater core. If slight heating is desired, only some air will pass through the heater core. If no heat is desired, all air is diverted around the heater core.

Max
 

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Ok...... So the heater core is always going full blast....

So it goes through the evaporator case first, and then goes through the heater core case....... I see how it is :thinker:
 

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Elwesso-I'm with you. I've never understood why it operates the way it does. It made more sense to have the hot water shut-off valve rather than to always have hot coolant flowing through the core. I'm sure it came down to a cost issue.

Max
 

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Funny...... It seems as if it would be CHEAPER to have the shut off valve...... Plus it would save space, since there has to be 2 seperate areas........

On my car, there is one "box", where the heater and evaporator are..... The AC is always on, unless its in ECON mode...... Then the amount of heat is controlled by the valve.......
 

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1993 Sixty Special, 1991 Allante
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ireman said:
Hey folks, new to this forum and in need of some assistance (a lot of assistance my wife says, but that's for a different forum I'm sure!). I have a '96 DeVille with about 105K miles on it. I dig it (of course), but when the weather turned chilly a few weeks ago I dialed in the temp to something more suitable than the 45 my outside temp was reading. To get to the point: my heater didn't heat anything. Regardless of what temp I set it only blows cold air. I checked the fuses (on the back of the rear seats from the trunk) and there was no fuse labled heater, but all of the fuses there checked out OK. Is there a fuse block under the hood? Is there a fuse for the heater? Am I looking at huge dough to heat myself up? Thanks a TON for any assistance you may be. Take care.

K.
My '93 Sixty Special never did heat very well in the first year I owned it. Earlier this year I took it in to change the anti-freeze, hoses and clamps. The mechanic told me the thermostat was stuck open and he replaced it. Guess what! Instant heat and GOOD heat. Additionally, and I know this sounds weird, my gas mileage improved, too. :wave:
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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I was about to mention the thermostat too. If it's stuck open it can take longer for the engine to warm up.
 

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2005 CTS-V, 1994 Infiniti Q45
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COMPLETELY normal..... The ECU thinks the engine is running too cold, and it makes the car run rich......
 

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ECU= engine control unit, also referred to as the PCM.....

Layman term= the computer......
 

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Discussion Starter #16
OK, here is the latest update.

I checked out the door that directs what air where, the heater core, fluid level and thermostat. All are kosher. The dealer (after taking $175) gave me a blank stare and a shrug of the shoulders. I think one of the techs said thanks for his kids new braces though (lol). Thanks again for the suggestions folks. If I don't shoot the car first I'll let you know what happens. Take care.

K. :banghead2
 

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ireman said:
OK, here is the latest update.

I checked out the door that directs what air where, the heater core, fluid level and thermostat. All are kosher. The dealer (after taking $175) gave me a blank stare and a shrug of the shoulders. I think one of the techs said thanks for his kids new braces though (lol). Thanks again for the suggestions folks. If I don't shoot the car first I'll let you know what happens. Take care.

K. :banghead2
I assume that your blower is operating properly? You say you checked the door that directs the air. There are 4 of them. Are you sure you checked the right one? One directs air to the top and bottom, one directs air to the windshield, one directs outside air and the last one directs either warm or cold air. You also said you checked the heater core. What did you check? The basic heater system is not very complex. You have hot coolant cycling through the heater core which makes the core very hot. Your blower then blows through the heater core which makes the air entering the passenger compartment very warm. If you have cold air entering the passenger compartment either there is not hot coolant entering the heater core or the hot heater core is being bypassed and only cool air is entering the passenger compartment.

Max
 
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