Hi All,
Newbie here.
My vehicle is equipped with the automatic temperature control.
All last winter the front passenger and driver area had very little heat but in the summer, the temperature settings and controls were ok. Well, now it is getting cold and again, the front area is cold. I've verified that all three actuators are working, hot water to the heater coil, and during troubleshooting, my friend (mechanic) noticed my AC coming on with both front temp settings on Hi. The snowflake symbol was also on. I then disconnected the AC pressure switch so the AC compressor will not come on and now I have plenty of heat. It appears that while the vehicle was in Heating Mode, the AC was also on. The heat and fan will modulate to satisfy the temperature settings with the safety switch disconnected.
Is my Automatic Temperature Control module causing this problem?

Thanks,
Mike

 

The a/c will run if the vehicle is in defrost mode. Even if the compressor was running, you should still have heat. It is the same as taking in 0 degree air in the winter time. You could have a heater core plugging so without the cold air it can heat sufficiently but adding cold air it can't keep up.

 

I don't think it's the defrost mode as I had it set manually for hi heat, even in auto mode it was the same.

 

doesn't really matter, you should still get plenty of heat even with the a/c compressor running, that is what the blend air door is for. When you have the van hot and you touch the heater hoses coming from the heater core, are they both as hot as the radiator hose or is one cooler than the other? (it will still be hot, just not as hot as the other)

 

Thanks for your advice Tizzy1.

I've had 110 deg F coming out of the vents with the ac disabled.

why would the defrost (AC) be on when it's not selected? anyway, I found that since I've disabled the AC from coming on, the recirc mode and ac would come on even if I turn them off, they will automatically come back on within a minute. I think that the climate control system senses the incoming air temperature, remember I'm from Canada and it's getting colder here (50degF in the mornings), and it thinks it's hot outside and the system wants to turn on the AC. The blend and mode doors will do it's thing to control the occupancy comfort as per settings. Since the ac is disabled, the temp in the mixing box is reading high, that is why i think it's going into recirc mode. It never went into this mode with the ac running.

I'm thinking that it's some ambient sensor that senses the air temp has gone bad and is reading a very high temp. That is why the AC is always on. I doubt its the climate control module.

How many sensors are there and where are they located?

Anyone else with suggestiions?

Thanks

 

Anytime the a/c system has a problem the default is the defrost and floor vents. I would recommend to have the van check for ant stored codes in the hvac system.

 

The temp sensor is the little silver circle right below the center dash vents. It is an infrared sensor that senses body temp. It looks at the drivers and passenger seat areas. If there is an issue with the temp sensor, you would need a scan tool to check it and see what it's reading.

 

Update:
I've been troubleshooting but still haven't solved the problem. Steps I've taken are:

- I've taken off the actuators for both passenger and driver side and verified the blend doors operate at full stroke as I can hear them go from stop to stop, so I don't think there is a problem with the door hinges
- I've watched both electric actuators turn in one direction when I set the climate control in calibration (actuators removed). This verified that it at least turns one direction and I believe its to full cooling
- heater core was flushed
- the heating and cooling cycles have worked intermitently but usually fails to very low heat in both the front drivers and passengers side.
- today with the outside temp at 8 deg c (46 deg F) and with little heat, I was able to visually inspect that the actuator for the drivers blend door at full stroke to heat but cannot tell what the passenger's side position was

Does anyone have an airflow diagram of the ventilation system with the heater core, evaporator, blend and mode doors? This would help me in troubleshooting.

Is it possible that the passengers blend door actuator is not turning and causing very little heat for passenger and driver? My next step is probably to swap the actuators from passenger to driver to see what happens.

Regards,
Cold Mike

 

One heater hose is hotter than the other.

Mike

 

probably have a plugged heater core then, they should both be very hot