heater woes

[turborabbit]

Hey, Vdubyas, it got cold here and I lost my last working speed (high speed) on my 1981 Caddy heater control and antifreeze vapor started coming out my defrost vents and I'm losing antifreeze with no apparent leaks. Hmmnh, I suspect these issues are connected. How deep do I have to go to fix this unfortunate situation? I have lots of spare Caddy's and parts. :cry:

[zukgod1]

Sounds like you have a leaking heater core.

I've not replaced one in a mk1, I hope for your sake they aren't as bad as the mk2. Not that the mk2 is really all that hard just time consuming.

Sounds like the resistor is toast on your blower as well.

Time to tear it apart.

[Quantum TD]

Use the search function. Someone did a post on this not too long ago. On the Rabbit, you have to pull the heater box which involves removing the dash (a real treat). It also involves disconnecting the AC, if your car is equipped.

I'd say just swap in a whole heater box, but you never know if the replacement will be any good unless you test it. I usually submerge the heater box in a bucket of water, and then put  compressed air to it and look for bubbles. The big thing is to turn the pressure WAAAAY down, to about 20 PSI. Anything over that might blow a good core.

Also, it might be a good time to fix all the sloppy foam inside the box (AC cars). There's a great writeup on VWVortex for the MK2, but you can get the idea for your car.

As for the heater speeds: it's probably one of the following:

1) Heater resistor (Non-AC cars: it's mounted to the blower motor).
2) Heater Relay (mounted to the driver's side of the airbox on AC cars).
3) Heater resitor (AC cars, it's mounted to the passenger side of the box)

[AudiVWguy]

Does your caddy have AC?

[fatmobile]

You should never have to pull the heaterbox to change the heater core,... AC or not.
 If it has AC it's easier to cut a hole in the side of the box and pull it out,.. then make a flat cover for it.
 AC is even easier than non-AC once the slot is cut,... the heater core is out away from the accelerator.
 I made a post on here and showed a picture of where to cut,.. you can see right where to cut; along ridges in the plastic.
 I'm guessing switch is bad,... or a fuse.
 High is directly to the fan motor,... no resister in the way.

[the caveman]

Rabbit heater core replacement time - 2 hours. just have to cut the side of the box where it sits. replace and reseal.
 Mk 2 golf/jetta diesel core without A/C,replacement time 1 1/2 hrs tops. Remove center console, underdash trays, whole heater box comes out. remove core ,wash reinstall wash hands.
 MK3 golf/jetta and B3 passat, 3-4 hours. take out dash,keep track of all the screws, look where the body  welds match up under the windshield, swear while trying to figure out how to reseal . replace clutch cable also. Easy when dash is out, a real pain when in.