Hymie

Can anyone help with my 2000 WJ (with Automatic Zone Control) heater problem?

All vents blow out cold air, regardless of the temperature control settings.

Both hoses to the heater matrix/core are hot, when the engine is at temperature.

Running the AZC self-diagnostic check, results in the display cycling through the fault codes:-
52 – Al (Recirc) door travel range too large
54 – Left temperature door travel too large
56 – Right temperature door travel too large

When I enter the system parameters mode; the left side temperature target position (in ratio) reads 255 (from a possible range of 0 to 255) and the corresponding right side temperature target position also reads 255. Using manual control to adjust either of these parameter values (from 0 to 255) does not result in warm air entering the cabin.

However on one occasion, following adjustment of the parameter values, when I later drove the vehicle, resulted in the vents blowing out warm air regardless of the temperature control settings – but reverted back to cold air the next time I drove the vehicle.

With the fan set to minimum flow, when using manual control to adjust the parameter values for the Air inlet target position – I can hear the operation of the relevant motor. When adjusting the temperature target position parameters, I cannot hear an adjusting motor sound from the heating system.

Any help/advice appreciated.

Bustedback

Check your coolant level in the radiator.

Hymie

Having searched this site – I have found the solution to my problem at www.heatertreater.net.
It appears to be yet another Jeep design fault.
Although the parts cost upwards of $120, plus a few hours work – I guess I’ll have to order the parts and make the repair.
Before they arrive, I might try to effect a manual fix (with heating always on) now that winter is coming.

candymancan

Do you have al imited ? These codes to me sounds like the blend doors are gone and need to be fixed.

Hymie

Yup – the heatertreater.net link gives this as the fault, along with the re-circulating selection flap.
I don’t really care whether the heated air is from within the cabin or from outside – just as long as it is hot.