94 heater not heating
Thread Starter
Instructor
Joined: Jul 2009
Posts: 242
Likes: 7
From: Bowling Green KY
94 heater not heating
Hi,
I looked around for a thread and just got confused. My A/C blows strong and cold, but when I turn on the heat, it blows strong and cold still. No heat.
I've heard that the heater core and hoses can be accessed through the engine side, but I've also read that it requires dash removal.
Any ideas?
Bob
I looked around for a thread and just got confused. My A/C blows strong and cold, but when I turn on the heat, it blows strong and cold still. No heat.
I've heard that the heater core and hoses can be accessed through the engine side, but I've also read that it requires dash removal.
Any ideas?
Bob
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
The heater hoses are accessable from the engine compartment, not sure about the heater core.
However, you might want to first check to see if the hoses are connected to the heater-core.
Also, check both hose's temperature (by touch or IR temp sensor), if both about the same (hot), problem may be the air mixture 'door' and not a clogged heater core.
One hose ('u' shaped) should be connected to the underside/forward pointing connector below the black 'surge' (Pressure) coolant tank (by windshield).
The other hose should be connected to the water pump, and mid-way (just rearward of passenger side tire) should have a plastic pressure limiting valve (reduces flow pressure to heater core during WOT).
One other possible problem is a clogged heater core. However, other members have sucessfully un-clogged theirs with repeated flushes (i.e. with a garden hose) WITHOUT having to remove the heater core from the car.
However, you might want to first check to see if the hoses are connected to the heater-core.
Also, check both hose's temperature (by touch or IR temp sensor), if both about the same (hot), problem may be the air mixture 'door' and not a clogged heater core.
One hose ('u' shaped) should be connected to the underside/forward pointing connector below the black 'surge' (Pressure) coolant tank (by windshield).
The other hose should be connected to the water pump, and mid-way (just rearward of passenger side tire) should have a plastic pressure limiting valve (reduces flow pressure to heater core during WOT).
One other possible problem is a clogged heater core. However, other members have sucessfully un-clogged theirs with repeated flushes (i.e. with a garden hose) WITHOUT having to remove the heater core from the car.
Instructor
Joined: Mar 2009
Posts: 136
Likes: 0
From: South Carolina
Have you removed the thermostat or someone previously before you? If so, you will not get the heat you desire. To check, if you temperature is not getting up past 150 or so, you need to get one.
Drifting
Joined: Dec 2003
Posts: 1,493
Likes: 94
From: Westfield MA
Could be your thermostat, easy enough to check, just look at your temp to see if it is at least 190, could be the blend door, just take the sensor out of the top of the box that is in the engine compartment and you can look in and see the blend door, cycle the temp from low to high and you should be able to see it move. The most common problem, it seems, is a plugged core. Both hoses will be warm even with a plugged core, but if your temp is up and the blend door is working, just take the hoses off and give it a blast with a garden hose. That is what it took to make mine work and it has been fine since.
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Thread Starter
Instructor
Joined: Jul 2009
Posts: 242
Likes: 7
From: Bowling Green KY
Thanks for all of the help. I checked the two hoses, and the top one going to the heater core is hot of course, after the limiter it's still hot but not as bad, the bottom U shaped hose is cold.
So that probably means that the door is okay I would guess, and the core is plugged. Would you agree?
I'll try the hose thing this weekend to flush it.
So that probably means that the door is okay I would guess, and the core is plugged. Would you agree?
I'll try the hose thing this weekend to flush it.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Thanks for all of the help. I checked the two hoses, and the top one going to the heater core is hot of course, after the limiter it's still hot but not as bad, the bottom U shaped hose is cold.
So that probably means that the door is okay I would guess, and the core is plugged. Would you agree?
I'll try the hose thing this weekend to flush it.
So that probably means that the door is okay I would guess, and the core is plugged. Would you agree?
I'll try the hose thing this weekend to flush it.
Looks like you on the right track, Theadmiral94 has good info. Fix what is wrong first, then see if you have to go further.
Also if you have not changed the coolant in the last 2 years I suggest you drain as much as you can and give the radiator a basis flush. Flushing the heater core is easy. Take hose off the plastic fitting, and the other one to the tank. Flush both ways till clear several times with only moderate pressure.
