AC question...

4RF RDS

Well-known member
I have a Land Rover underdash AC unit in my Td5 110 (it came from the factory this way). It has worked great for the last three years but this summer it freezes up every time I drive it. It freezes the lines from the compressor to the evaporator. Have been driving using it by turning it off then full blower till unfrozen. I want to get it working properly.

Question is where to start or what to do when looking for the problem? Check pressure in the system? Expansion valve? Working on these underdash units is a PITA. Anyways any help is appreciated.

Cheers
 

jafir

Founding Member
If it's freezing, normally it's either low on refrigerant or it's got an airflow problem in the evaporator. I don't think these system have thermostats in them to keep the from getting below freezing by cutting off the compressor, like some cars do.

EDIT: this isn't land rover specific experience, just what I've experienced on other vehicles, but the principals are all the same
 

jymmiejamz

Founding Member
Callsign: KN4JHI
The fact that it used to work fine and now you are having an issue would lead me to believe that you may have a small leak and are low on refrigerant.
 

Leadvagas

Member
Low charge simptom. Pull the charge and see whats there. Hopefully you have a charge weight noted some where on the system. Then you can either charge it up to 250 psi with nitrogen and bubble check for leaks (preffered method) or you can have dye put into the system with a refrigerant recharge. Be warned the dye is like blood it inevitably gets all over the place. About 90% of the time in automotive systems the leak is on a soft line. If the charge is not short, then you are looking at a metering device (TXV etc.). You might want to throw a high side gauge on it first thing, if the metering device is plugged or failed your high side presures will be well over 250 and suction will be under 35 psi
 

4RF RDS

Well-known member
Thank you for the feedback thus far. The evaporator also makes noises like marbles rambling inside the unit if that helps anyone provide further possible diagnosis.

I found on another forum that the Coolair system (the one I have) does in fact have an electronic control unit (inside the plenum near the switch panel) that is suppsed to prevent freeze up. It works in conjunction with a temperature probe on the evap unit. Apparently it can fail... Being eighteen years old I suspect that this could be a possibility as well, however a leak seems probable.

I'll have it pressure checked as identified above and will provide feedback once I have something to report.

Regards and thanks.
 
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