heater not working
Thread Starter
3rd Gear
Joined: Apr 2013
Posts: 3
Likes: 0
heater not working
I have a 1994 C4 and the heater doesn't work, is there a valve that could be stuck or does anyone know whats the problem and how to fix it? The air just doesn't get warm no matter how hot the engine gets. Any help will be appreciated.
Instructor
Joined: May 2013
Posts: 184
Likes: 4
From: auckland
good question my brother has the same problem, im not sure on valving but over the years i have always found little radiator up in the dash will be blocked ,major job to remove according to book good luck,let me know if you find something else were open to sugestions
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
I don't know if it applies or not, but on my '94 to '96 Impalas/Caprices the heater is common to not blow hot air. On these it is easy to fix though.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) I have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) I have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
Melting Slicks
Joined: Mar 2008
Posts: 2,351
Likes: 222
From: Delta B.C. Canada
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One other thing to check: There is a restrictor in the inlet hose to the heater core. You can find it in the area just in front of the surge tank. It's posible for crap to clog up the hole in the restrictor, thereby blocking hot coolant from flowing to the core. You can easily check this by holding the out-flow hose from the heater core....it should be about the same temp as the inlet, when the enine is running.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
i don't know if it applies or not, but on my '94 to '96 impalas/caprices the heater is common to not blow hot air. On these it is easy to fix though.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) i have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) i have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
Racer
Joined: Oct 2012
Posts: 350
Likes: 2
From: Huntsville AL
I don't know if it applies or not, but on my '94 to '96 Impalas/Caprices the heater is common to not blow hot air. On these it is easy to fix though.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) I have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
The heater core fills up with some kind of sludge. Disconnect one end of the heater hoses and use a garden hose to flush/backflush the heater core. (you don't want to fully seal the garden hose to your heater hoses since the pressure will be too high up to about 45 psi. Just shoot water in the ends of the hoses is enough to cause a flow.) I have had three of those cars and all of them had that problem and a garden hose flush cured all of them.
Good luck.
There's always lots of discussion on this problem in the forums in the fall/winter time in the lower 48. Clogged heater cores seem to be a common problem. As advised, flush it out, both directions, but be careful to not over pressure the core.
Instructor
Joined: May 2013
Posts: 184
Likes: 4
From: auckland
ITs winter down under here at the moment New Zealand snow bound you guys get your turn at Xmas,
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
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Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
No heater control valve on a 94, coolant always flows.
After the engine comes up to temperature, grab the heater hoses and feel the temperatures. They should be as HOT, and as hot as the larger hoses to the radiator and surge tank. If the heater hoses are just warm the heater core is clogged.
It's easy to clean it out by disconnecting the two hoses and running water thru it in both directions. One hose goes to the surge tank and the other to the plastic fitting. Run a garden hose thru the core at LOW pressure in both directions.
On a personal note, when I got my car it took me about 12 times of back and forth to clean the core and for it to run clear (lots of crap came out). I found out at least for me I have to clean the core every one or 2 years for it to not clog again and to have heat when I need it. Every 2 years I do the coolant anyway so just do the core as a added bonus.
If the heater hoses are hot and water flow is not the problem, then the blend door will needed to be addressed which is another problem, investigation and repair.
After the engine comes up to temperature, grab the heater hoses and feel the temperatures. They should be as HOT, and as hot as the larger hoses to the radiator and surge tank. If the heater hoses are just warm the heater core is clogged.
It's easy to clean it out by disconnecting the two hoses and running water thru it in both directions. One hose goes to the surge tank and the other to the plastic fitting. Run a garden hose thru the core at LOW pressure in both directions.
On a personal note, when I got my car it took me about 12 times of back and forth to clean the core and for it to run clear (lots of crap came out). I found out at least for me I have to clean the core every one or 2 years for it to not clog again and to have heat when I need it. Every 2 years I do the coolant anyway so just do the core as a added bonus.
If the heater hoses are hot and water flow is not the problem, then the blend door will needed to be addressed which is another problem, investigation and repair.
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
It is possible that you also could have air inside the heater core, a neat little trick people do is open your radiator pressure cap, and jack the car up in the front so that the highest point in the system is the radiator neck. Turn your heat on, and run the car for 15-30 minutes. Some coolant may spill out but just top it off when you're done. This will allow the air to bleed out of the system.