gravey

Hi All,

I've got a fairly complicated situation - so don't assume the usual suspects.

My Problem: I'm getting very limited amounts of heat out of the heater when the car is up to temp.

Factors: Last April, I repaired the evaporator. At the same time that I had the heater box out, I installed a new heater core. The heat hasn't been the same ever since. This thing used to pump out so much heat that you couldn't run it full blast.

At first, I tried to talk myself into the fact that maybe the heat actually had stopped working before I performed the repair (possibly because of a thermostat or a water pump.) Now, I'm starting to reconsider the heater box.

In an attempt to rule out the thermostat or blockages in the heater core, I reverse-flushed the core two days ago, and installed a new thermostat. The system runs a little warmer, but still never gets "hot"... only just warm. Hoses running to- and from- the heater core are both hot. The system temp rises to slightly past the halfway mark between 100 and 210, and then maintains that temp.

In my mind, the problem has to be coming from either (a) the coolant flow path (thermostat/water pump/heater core), or (b) the actual heater box mechanism (specifically, the blend door.) When I performed the A/C repair, I tried to do a decent job of sealing the areas around the heater core and evaporator so that air could not flow around the component, only through it. I suppose it's possible that the blend door isn't fully able to close due to excess foam, but I am able to watch the blend door motor move the door as I turn the **** from cold to hot. Every click of the temp dial further towards heat moves the motor slightly, and only the final "click" does nothing. I'd be curious to compare that with a working system to see if a known-good door has some motor travel even on the final click of the temp dial.

One final note: when letting the system come up to temp by idling it, the heat temperature is noticeably warmer than after you start driving the car. You can feel the air temp cool down a bit after the car is in motion.

Fire away with question, comments, suggestions... And thank you VERY much in advance for any help.

kjc

You said, "Factors: Last April, I repaired the evaporator. At the same time that I had the heater box out, I installed a new heater core. The heat hasn't been the same ever since. This..."
*I believe that's the answer to your problem.. specifically, the part about sealing around components to block air flow. Try again. ;-)