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ICEmarc
20-03-2012, 04:02 PM
Hi
I'm hoping somebody can help me diagnose a faulty Tev (possibly)

Airedale R407c air conditioning unit

Discharge 255psig sub cooling 13'c (ambient air 17'c)

Suction 35psig superheat 32'c

I have noticed icing on the distributor after the Tev

sedgy
20-03-2012, 05:52 PM
hi icemark,
at 35 psig the evap tamp is -10 c what temp is requiered ? in the room space? sedgy

ICEmarc
20-03-2012, 06:38 PM
The desired room temp is 20'c

monkey spanners
20-03-2012, 10:24 PM
Whats the air flow through the coil and filters like?

Does the suction pressure change it you warm the phial?

leegally1983
22-03-2012, 01:31 PM
Icing on the distributer could be lots of things i.e. short of refrigerant blocked filters loss of fan motor. if its not anything obvious i would decant the gas see if it is short if it isnt replace the TEV, filter drier and give it a good VAC ...... simples

aramis
22-03-2012, 10:11 PM
There are many causes for high condensing and low suction pressures like oversized compressors, faulty expansion valve, pressure drop somewhere, overcharge, etc.

Also things I suppose you already checked obvious things like not having incondensables and you followed correct charging procedures for R407c and it is in the correct composition.

I would start with the condenser because it is more "off":

Make sure the fan is rotating in the correct direction with no short circuits like open panels. Seal any losses.

Run your hand on the condenser's air intake and make sure you do not feel air at a higher temperature than your ambient temperature (measured far away from any unit). If the temperature at the inlet is higher than ambient or you feel gusts of hot air, you have a hot air recirculation problem.

Check the airflow of the condenser. This is not easy and please don't post back that you cleaned it. Just make sure that the airflow is correct through every little hole in the finns!

For this you either use a anemometer but better still a lantern held from the inside of the unit and somebody watching on the outside the light pattern. If it differs anywhere you may have a blocked condenser and you should use a hard wire to clean it.

If you have any of these problems and solve them you will probably find that the refrigerant charge is low, recharge.

Anyway post back your progress.