Heater Problems
Thread Starter
Racer
Joined: Oct 2004
Posts: 288
Likes: 18
From: Somerset PA
Heater Problems
Hello! I just bought an 89 Coupe, and am having some trouble with the heater. It never blows hot air. I've let the car run for 15 - 20 minutes, and it never even got warm. Also, I noticed that the air conditioning compressor continues to go on and off at regular intervals weather I set it to 60 or 90. Does anyone have any suggestions on what I should check? Thanks!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Assuming the air is flowing from the correct vents, the heater core is probably plugged and when that happens, water flows over the top of the core, but not through it. You can try to flush it by disconnecting the hoses and hooking up a garden hose to it, or use compressed air, but most need to be replaced. Also, check out the condition of the coolant. If it it looks bad, replace it and keep a close eye on it as the '89 head gaskets can leak and set up galvanic corrosion (which is one of the reasons the heater core plugs up).
A/c compressor should cycle less than 8 times per minute and really not at all if it's above 70 degrees with engine at operating temp. If it cycles more than this, the charge is usually low. Look for compressor oil on the hood above the compressor. If it's there, the shaft seal is shot and needs to be replaced (kits are available at NAPA for about 50 bucks). Otherwise, the Evaporator may be leaking. Any frost on the windshield? Best to have it pressure/leaked checked either at an a/c shop or if you have access, with a manifold gage set.
A/c compressor should cycle less than 8 times per minute and really not at all if it's above 70 degrees with engine at operating temp. If it cycles more than this, the charge is usually low. Look for compressor oil on the hood above the compressor. If it's there, the shaft seal is shot and needs to be replaced (kits are available at NAPA for about 50 bucks). Otherwise, the Evaporator may be leaking. Any frost on the windshield? Best to have it pressure/leaked checked either at an a/c shop or if you have access, with a manifold gage set.
Drifting
Joined: Sep 2004
Posts: 1,614
Likes: 3
From: Richmond Va
Cruise-In VI Veteran
Florida
Originally Posted by 1quik91
Move to southern Florida, never had my heater on! 
Glad to see you are ok there though.Bob
Thread Starter
Racer
Joined: Oct 2004
Posts: 288
Likes: 18
From: Somerset PA
Thanks for the info! I'll check on the core ASAP. It's about to be put away for the winter, but I'd like to get the problem taken care of before I do.
As for moving to FL, Well, if I did that, I wouldn't need to have 2 vehicles, and could afford a much newer vette. However tempting that is, I think I'll stay here in PA.
This is a great forum! Thanks for your quick replies!
As for moving to FL, Well, if I did that, I wouldn't need to have 2 vehicles, and could afford a much newer vette. However tempting that is, I think I'll stay here in PA.
This is a great forum! Thanks for your quick replies!
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Heater core is tackled from the inside, passenger side, lower firewall. It involves removing whatever is in the way, unbolting the front half of the heater/a/c plenum and removing the core. First step is to remove the hush panel covering the underside of the passenger's dash. That will let you see what else needs to come out to access the heater box screws.
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Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Originally Posted by johnash
Hello! I just bought an 89 Coupe, and am having some trouble with the heater. It never blows hot air. I've let the car run for 15 - 20 minutes, and it never even got warm. Also, I noticed that the air conditioning compressor continues to go on and off at regular intervals weather I set it to 60 or 90. Does anyone have any suggestions on what I should check? Thanks!
My Mercedes did that. Problem, there wasn't enough coolant in the engine to get into the heater core. (Bad water pump).
Chk the valve to see if its hot. If its hot on one end and not the other the valve doesn't work. Chk both hoses one is hot in the other is cooler out.
Usually a core that is bad will leak. If its blocked then you'll have to replace both the heater core and the radiator. They will both be blocked since they're both on line together.