Heater Trouble...1988
Thread Starter
Burning Brakes
Joined: Feb 2004
Posts: 1,024
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From: Long Island New York
Heater Trouble...1988
Hey guys, trying to get the bugs worked out...I know I won't be needing my heat for awhile, but i may need the defroster and I can't get any hot air from the vents at all. I'm Not at all familiar with the electronic heater contols in the 88 I just bought (my 85 had the standard controls) and was wondering if anyone has ever experienced trouble like this and can point me in the right direction.. System is full of coolant, both heater hoses are hot, I even disconnected the A/C compressor to ensure it wasn't pumping through the evap, still cold. It seems as if something perhaps may not be "switching over." The controls seem to be set correctly. I have only looked this over at night; also considering a heater conrol valve problem...If this car has one, (i'm pretty sure it must) Where should I start looking? Any advice would be greatly appreciated. Thanks in advance all!
Jack
Jack
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Heater Trouble...1988 (Jloshotz)
Assuming the blower is working and the air is coming out of the correct vents, sounds like the heater core is plugged up. When it is, coolant flows across the top of the core but not through it. Try to flush it with compressed air or by hooking a garden hose up to it. Check the condition of the coolant too. Early aluminum head motors weren't very kind to the head gaskets leading to galvanic corrosion with one of the symtoms being a plugged heater core.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Re: Heater Trouble...1988 (Jloshotz)
I had the same problem in my 89. after I checked all the obvious things, (heater hoses, heater door, thermostat) I finally did a search in this forum and found that there's a black box about 3"x5" above the gas pedal which has a circuit board inside with several vacuum hoses attached.
After removing the knee pad and a 7mm screw holding the box, you can remove the box from the mount and open it up, inside you can remove another couple of screws that hold the circuit board in place. carefully turn the circuit board over and you'll see two solder joints that have broken loose. Just carefully solder the joints back and everything will work fine.
It's really tough to get to everything since it's in an awkward position under the dash. Some will say to mark and remove the vacuum hoses so the circuit board can be removed from the dash to be resoldered but, The vacuum hoses were very hard to remove so I just repaired everything with the board still attached in the vehicle. Everything worked perfectly afterwards.
[Modified by GKK, 8:03 AM 4/28/2004]
After removing the knee pad and a 7mm screw holding the box, you can remove the box from the mount and open it up, inside you can remove another couple of screws that hold the circuit board in place. carefully turn the circuit board over and you'll see two solder joints that have broken loose. Just carefully solder the joints back and everything will work fine.
It's really tough to get to everything since it's in an awkward position under the dash. Some will say to mark and remove the vacuum hoses so the circuit board can be removed from the dash to be resoldered but, The vacuum hoses were very hard to remove so I just repaired everything with the board still attached in the vehicle. Everything worked perfectly afterwards.
[Modified by GKK, 8:03 AM 4/28/2004]
Thread Starter
Burning Brakes
Joined: Feb 2004
Posts: 1,024
Likes: 0
From: Long Island New York
Re: Heater Trouble...1988 (Jloshotz)
Excellent, thank you for your insight. I thought the heater core was flowing because both hoses were hot, but i'll check that. And i'll definitely look for that black box, too!
:thumbs:
:thumbs:
Le Mans Master
Joined: Jul 2001
Posts: 8,183
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From: Santa Maria, CA
Re: Heater Trouble...1988 (Jloshotz)
Jello,
when you go to flush the heater core, be VERY gentle handling the core's 2 pipes. At their age, could easily tear one and you do not want the massive PITA job of replacing the thing. Possibly you could pour in a few hours ahaed of time some of that cooling system cleaner stuff and then flush the whole system. Then while in there reverse flush the H/C.
The car does not have a heater valve.
Click the search button, type in "no heat" in the search field, choose "archives", choose "C4 Tech"
and lots of good info will come up. my bet is this:
http://forums.corvetteforum.com/zerothread?id=202649
here is another good one:
http://forums.corvetteforum.com/zerothread?id=766884
IM me if need more help
when you go to flush the heater core, be VERY gentle handling the core's 2 pipes. At their age, could easily tear one and you do not want the massive PITA job of replacing the thing. Possibly you could pour in a few hours ahaed of time some of that cooling system cleaner stuff and then flush the whole system. Then while in there reverse flush the H/C.
The car does not have a heater valve.
Click the search button, type in "no heat" in the search field, choose "archives", choose "C4 Tech"
and lots of good info will come up. my bet is this:
http://forums.corvetteforum.com/zerothread?id=202649
here is another good one:
http://forums.corvetteforum.com/zerothread?id=766884
IM me if need more help
