: No hot air when on defrost or heat

water walkin warrior
09-20-11, 04:23 PM
I was looking at my FSM to see what to look for regarding no hot air when the defrost or heat is turned on. I've got to do some checks tonight. Does anyone know of any specific reason I may not be getting hot air in my '89 Brougham. It's getting chilly in the mornings and heat would be good before winter comes.

By the way, she isn't using oil like she was before. So the oil problem is pretty much fixed for now.

09-20-11, 05:28 PM
probably heater core problem. probably plugged up. flushing it is pretty easy and quick.

09-20-11, 05:38 PM
First check the engine coolant temp is around 200 degrees . If it is check the hoses going from the engine to the heater core (smaller rubber hose coming off the back of the intake and going into the firewall ) see if one or both are hot . If only one is hot that means coolant is flowing to the heater core and not out (heater core is clogged ) . If both hoses are cold and the engine is warm there may be a restriction in the passage from the intake manifold . Dont forget to check the basics like coolant level or if coolant was recently drained make sure the system has been bled of air .

09-20-11, 08:25 PM
There is a heater control valve connected to the two hoses that go the heater core. If both the hoses are cold, it could mean that the valve is stuck closed. The valve is vacuum controlled, so try replacing the vacuum line.

My heater control valve will get stuck closed if I accidentally put the defrosters on at 60, and then I wont have heat for the rest of the drive. Sometimes I can get it to open if I tap it with the handle of a screwdriver.

09-25-11, 12:33 AM
Once both heater hoses are hot, even if you had to bypass the heater control valve, there is only one other reason for no heat. There is a black plastic unit behind the glove box bin with a little motor and metal rod called the programmer. It is very common to go bad and should still be available at places like A/C delco or Rock Auto for around 150.00 Used ones can be had on ebay for around 50 usually but its hit or miss to see one working with some kind of warranty. You always have option of propping the metal rod to full heat for winter season and vice versa.

water walkin warrior
10-07-11, 01:12 PM
One of the hoses is not getting hot. It's the one on the left with the cap that screws off on the left side of the air filter. The other is getting hot. Antifreeze should be ok. I just put new antifreeze in since I had to change a fairly new thermostat that got stuck in the closed position. (I bought a fail safe thermostat to replace it in case the problem would happen to happen again.)

Would that mean the heater core is clogged like said? How do I go about flushing it?

10-07-11, 01:55 PM

Check out here, I had to do it last year to my 95. should be about the same on all cars.

10-07-11, 05:29 PM
It sounds like the return line isn't getting hot, so the heater core is clogged.

10-07-11, 10:14 PM
Before flushing the system, confirm the heater valve opens and shuts. At 60 degrees displayed on the climate control panel there should be vacuum at the hose to the water valve holding it closed. At any temperature above 60, the vacuum should quit and the valve will open allowing hot water into the core. Simply pull the vac. hose off and feel for vacuum.