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edfred 09-05-2011 03:49 PM

strange working ac/heater WJ limited 2001
My ac/heater isn't working like it should.
At first when it's on automatic it works ok but after a while there is no air coming out of the vents.
When i turn it to manual and set the ventilator on high i can hear the ventilator is working but still no air coming out off the vents.
Also the ventilator unit is condensing very heavy so my girlfriend is getting her feet's wet.

Anybody any idea?

2005JGC 09-05-2011 05:46 PM

Re: strange working ac/heater WJ limited 2001
I wonder if your evaperator is freezing up solid. Will it continue to blow without the A/C on (just the fan)?

Frango100 09-05-2011 06:08 PM

Re: strange working ac/heater WJ limited 2001
First of all it seems that the water drain from the HVAC housing is plugged, causing the waterdrips on the passenger side. This drain comes out in the engine bay, so try to open it with some kind of wire.
When the airflow stops again, try to put it in full heat and see if after a while its starts blowing again. If yes, it was probably ice closing the evaporator.

edfred 09-06-2011 11:10 AM

Re: strange working ac/heater WJ limited 2001
Thanks for the reactions so far.

@2005GJC the fan continues to blow when i turn off the ac and after a while air will come out off the vents again.

@frango i don't think the drain is plugged because i discovered that the housing is becoming complete wet on the outside and even ice will form on it.

The problem wasn't a onetimer and happens each time i drive the car.

Icing up off the evaporator seems to be logical.
How is this possible?

Frango100 09-07-2011 12:45 PM

Re: strange working ac/heater WJ limited 2001
There is a temperature sensor on the evaporator which must take care that freezing of the moisture on the evaporator doesn't occur. It should switch the A/C compressor clutch off when a temperature of 1.1 C is reached and prevents in this way the freezing of the evaporator. Maybe this sensor is bad or the contacts of the connector corroded.
The bad thing is that you have to remove the whole HVAC housing (read complete dash) to get access to this sensor. There is maybe a way to measure it first before deciding to change it.
The 2 wires from this sensor are going to the Body Control Module, connector C2 points 16 (sensor signal) and point 20 (sensor ground). I have however no values for this sensor to know if its ok or not.

edfred 09-09-2011 11:16 AM

Re: strange working ac/heater WJ limited 2001
of course the switch is at a place that's hard to reach but anyway i'm gonna change it.
Went to the dealer and ordered a switch unfortunally they couldn't tell me what the best way to do it.
The new jeep dealer is a former lancia dealer this because off the merge with fiat.
They took an hour to program my rke wich is normally a 5 minute job.

Because i'm gonne take out the dash i will change the blenddoors at the same time.

If the fix worked i will let you know

Frango100 09-09-2011 03:57 PM

Re: strange working ac/heater WJ limited 2001
Jeep manual tells to open up the HVAC housing to get access to the evaporator. The temperature sensor is placed in the evaporator core. For some reason (and they donīt tell why) the new sensor has to go in a different hole in the evaporator core then the old one was installed into.

edfred 09-10-2011 12:16 PM

Re: strange working ac/heater WJ limited 2001
This sounds new to me.
I read the instruction in the manual on and this doesn't mention another position.
I'm going to look into this before removing everything.

Frango100 09-10-2011 05:43 PM

Re: strange working ac/heater WJ limited 2001
1 Attachment(s)
Here follows the page from the Jeep manual.

edfred 09-11-2011 10:47 AM

Re: strange working ac/heater WJ limited 2001
i looked into the manual i have and this page isn't in it.
Is this the manual for a 2001 WJ?
My manual mentions a low pressure switch on the accumulator but in the whole section of the ac (chapter 24) a switch like you mention isn't spoken off.
Strange isn't it?

I'm gonna check the switch on the accumulator first.

Frango100 09-11-2011 02:38 PM

Re: strange working ac/heater WJ limited 2001
My manual is for the 2004 WJ, didn't know that the airco system was different on older WJ's. Don't know then how evaporator freezing is prevented, when there is no sensor to sense it. On my WJ there is a pressure transducer in the line close to the condensor, but i don't have a low pressure switch, nor accumulator.

Frango100 09-12-2011 12:57 AM

Re: strange working ac/heater WJ limited 2001
I did download the manual from the nagca site and eventhough the manual is for 2001/2004 models, there are some differences in the airco system.
If your jeep has the accumulator (which is called filter dryer on mine), then it has a low pressure switch on this accumulator and a high pressure switch close to the condensor. Both switches are in series and connected to the PCM and can switch the compressor on and off. This low pressure switch has the function to prevent icing of the evaporator in this system. It is probably faulty on your jeep.

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