Please Help, Bad heater core?

[Dave97TA]

I just discovered that my heater is no longer working. My car isn't running hot and I haven't noticed any fluid leaking from under passenger side dash. Just wondering if anyone has come accross this. My A/C works fine, and i can crank temp control to far right and i feel a distinct temp change, however never gets very warm at all. Any suggestions? My car is a 1997 with only 68k, would a core go out that quickly? Please advise of anything i can check before getting raped at the dealership.

Thanks in advance!

[Jeff_in_Atl]

I have never heard of a heater core going bad without leaking. All it is a spiraling tube with fins on it. They don't get clogged or anything. My first question is what is your temperture gage showing? Are you loosing antifreeze?

[Dave97TA]

Yeah, no leaks or anything. Is it possible for there to be a blockage? Is there anything else that i can check? It just dipped into 50 degree temps here <I know, I know but hey I live in AZ> and my car typically runs between 185-200 or so. I'm not quite sure what else to check though. I'll check my coolant levels to make sure that i'm not leaking anything, but i haven't seen any puddles outside the car, or inside.

[Jeff_in_Atl]

I can't see how it could be clogged.

Check the vacuum diaphram that is connected to the flapper door that changes it from heat to cool. It's under tha dash somewhere. With the engine running, change the temperture adjuster on the dash and make sure the diaphram moves full travel.

[Dave97TA]

Thanks for the advice, I'll check that out first chance I get, i truly appreciate the help. And if anyone has any additional suggestions please let me know.

[00 Ragtop Z]

very likely a vacuum problem if everything else seems right. Just ahd to repalce the entire dash control module on my 92 RS becuase it was leaking vacuum on the heater line and the only way to fix was repalce because it was sooooo old.

[CLWILSON]

Originally posted by 00 Ragtop Z
very likely a vacuum problem if everything else seems right. Just ahd to repalce the entire dash control module on my 92 RS becuase it was leaking vacuum on the heater line and the only way to fix was repalce because it was sooooo old.

How where you able to determine that the control module had a leak, I still have not been able to figure out my heat problem and I am beggining to think that it is the vacuum parts on the module, but I don't hear them leaking.

[00 Ragtop Z]

a vacuum leak is simple. when you move form off to heater, do you hear a hissing sound? does it stop or does it keeping hissing? if it's a vacuum leak, it will sound like you have a tiny airhose under the dash (which in realityu is about what it is.)

[BAS]

come on guys

the HOT/COLD knob opens/closes a door, it is manual, not vacuum.

The other knob is vacuum controlled.

If you turn the selector to HOT and get no heat, you probably have a blockage
if your coolant temp is reading hot.

[CLWILSON]

Re: come on guys

Originally posted by BAS
the HOT/COLD knob opens/closes a door, it is manual, not vacuum.

The other knob is vacuum controlled.

If you turn the selector to HOT and get no heat, you probably have a blockage
if your coolant temp is reading hot.

I have replaced the heater core and the heater valve, where else could I have a blockage. The engine temp seems normal no overheating and runs at about 170 when it is warmed up. I can hear the door that you are talking about open and close.

[Rob B (shoebox)]

Re: Please Help, Bad heater core?

Originally posted by Dave97TA
I just discovered that my heater is no longer working. My car isn't running hot and I haven't noticed any fluid leaking from under passenger side dash. Just wondering if anyone has come accross this. My A/C works fine, and i can crank temp control to far right and i feel a distinct temp change, however never gets very warm at all. Any suggestions? My car is a 1997 with only 68k, would a core go out that quickly? Please advise of anything i can check before getting raped at the dealership.

Thanks in advance!

It is not uncommon for the core to get clogged. Disconnect the hoses and use a garden hose to flush the core, going in one direction, then other. This will probably restore your heat.

As BAS stated, the door and control for the heat is manually controlled (by a cable from the knob to the door), so there is no vacuum involved.

[00 Ragtop Z]

BAS--sorry, but teh ehater control is part of a vacuum system. It is NOT simply a manula system.

[Rob B (shoebox)]

Originally posted by 00 Ragtop Z
BAS--sorry, but teh ehater control is part of a vacuum system. It is NOT simply a manula system.

Read my post above. The heater temp control is on a cable and it not vacuum controlled.

[dochidalgo]

The vacuum valve is located...

behind the glove box...you'll have to unscrew a few ones...I saw a Trans am in the GM local dealer garage with the vacuum hose disengaged from its terminal.
Regards
Doc

[CLWILSON]

Originally posted by 00 Ragtop Z
BAS--sorry, but teh ehater control is part of a vacuum system. It is NOT simply a manula system.

It appears looking at the control module that the cable opens the door allow the air to flow over the heater control, but there is a vacuum line on the heat control as well that must control the vacuum driven heater valve that is under the hood. Listening a little closer I can hear a leak. Guess I'll try replacing the vaccum disk on the heater control.