I recently purchased an '01 VDP with 85K miles. The heater is acting strangely and I wanted to get some thoughts from the techs on these forums. The system only really produces heat when the temperature is set to "HI". When I start out in the morning with the system set to "economy" (i.e. no compressor) the heater works fine as long as "HI" is selcted. Any temperature setting below "HI" and the temp drops into the cool range. Also, as I am running errands, when I stop for a few minutes then restart and go again the heater will only blow cool air. Usually turning the system off for a few mintues while driving and then back on wil get hot air coming out again but not every time. Also as I stop and go (as in turning the car off and then back on again) the heat may come back on it's own but once the air starts getting cool it stays that way until I either shut the system off or stop the car and start up again. When I say that turning the temp a few degress lower makes the outlet air much cooler I mean this happens instantly. I don't see any way the heater core can change temperature that quickly so it seems to me it must be a flap issue. I'm comparing the functions of this car with a '97 that works as I would expect. So to be clear when I turn the system on I set the temp and select the outlet I desire (usually facia and floor) then set the fan speed and that is all I turn on. No "A/C", no "recirc" and no "auto". Any thoughts? Thanks!

 

If I move mine to "HI" the air temp gets very hot - So if the car is warming up properly and the air is not getting really hot then the heater core is not heating up properly.

And this can only be a flow issue. The system uses an electric pump to provide water to the core -- have you checked to make sure it is working?

If you do a search you will also find some information on accessing the ACC diagnostic -- it uses the control display -- this may help although I forget what you can get out of it.

Do you know if it has the original water pump and have you ever had any overheating issues -- the 01 should have the second generation of the pump -- but this still had problems.

 

Have you considered the thermostat? They act weird in many different ways. I leave my system on Auto and it warms up pretty quick. I never have the A/C / Climate Control off in my car. S.

 

I will have to go back through the records to see if either the water pump or thermostat has been changed. Will the heater core warm up even if the water pump for the heater doesn't work?

 

Yes, but the engine rpm needs to be higher than idle.

Last week I was in Wisconsin and mine decided that it did not want to produce heat on a 8 degree F morning even though the temp gauge showed the car was at operating temp. While I was on the freeway it started to produce heat.

My engine water pump and tstat are less than 1 year old so I think it's either the aux pump or some other restriction in the system. Gus did a post on a filter in the system that might need to be cleaned so I plan to do that and check the Aux pump real soon.

Ken

 

Filter ? Interesting - Do you have link? I can see how that could be problem if the wrong coolant and or mineral water is added/ mixed to the system.