Community Forums

martycap · 08-22-2016, 04:46 PM

2000 Newmar dutch star new compressor and drier. System vacuumed and recharged. Compressor clutch recycles lines at the evaporator frost up condenser fairly new and clean. No cold air can somebody please help me?

BFlinn181 · 08-22-2016, 05:15 PM

Are the dashboard vents blowing air and changing when you switch from floor to dash to defrost? Check the two heater hoses going to and from the heater and see if they are both hot when you are trying to use A/C. Often the heater control valve doesn't close all the way so heater core is actually battling with the evaporator coil in the fan plenum. You might have to adjust the heater control, or do as many have done and install a ball valve in the heater hose to stop coolant flow.

I don't know if it's punctuation or missing words, but I really don't understand, "Compressor clutch recycles lines at the evaporator frost up condenser fairly new and clean." Could it be the compressor clutch cycles on and off? Lines at the evaporator frost up and the condenser is fairly new and clean?

If you have frost forming on the hard lines going into the evaporator, that's a sign it's cooling, so all the more reason to suspect the heater is on too.

MtnTrek · 08-22-2016, 05:38 PM

Welcome to the forum,

Sorry to hear you're having troubles.
Armchair trouble shooting is just that... free and easy.
Just from what you've mentioned, the symptom's are indicative of a restricted air flow over the actual evaporator coil?
You mentioned that the system was serviced, by a professional? Assuming the charge was weighed in, meaning there was the correct amount / type added.
Is the inside blower fan operating at high speed, with a full volume of air from all open registers, not recirculating? The compressor on many models cycles on a low pressure switch on the liquid accumulator reservoir. Ideally the evaporator should be kept above freezing (pressure = temp.) where it only sweats. It requires warm air across it to fully vaporize the flowing liquid refrigerant.
Suspicions are the ducting, louvers, flaps, actuators, fan unit are not getting the warm air where it needs to be. The evap. coil could even be plugged up (air side)with airborne crud.
On rare occasions after a scattered compressor coughs up debris there can be residue that gets through to the orifice tube causing a restriction. A restriction in the suction line / metering device generally won't allow enough liquid to frost.

Be well.

Darwin · 08-22-2016, 05:50 PM

Suggest taking it back to the person who repaired, they can hook up gauges to the system and tell you if the ac is working very quickly. If it is cooling then start looking for problems with correct air flow.

Johndale · 08-22-2016, 07:49 PM

If you have good airflow at the beginning and then evaporator starts to frost over more likely it may be over serviced. Some people well say under service but in 45 years they were over. You should have a glass sight gage on the driver. If the unit is under service it will look like milk. On 134 you service it until you can count the air bubbles in the gage then stop. On the old stuff 12 you serviced it until no bubbles and add about 4 oz more. But you have 134. A sign of being serviced right it should sweat up to the compressor and about a 1/4 of sweat around the fitting. All of that said now I will get beat up again. Good luck and I hope this helps.

BFlinn181 · 08-22-2016, 08:14 PM

I've not seen a glass 'window' sight gauge in a R-134a system except R-12 systems that were converted to R-134a.

MtnTrek · 08-22-2016, 08:57 PM

Darwin Suggest taking it back to the person who repaired, they can hook up gauges to the system and tell you if the ac is working very quickly. If it is cooling then start looking for problems with correct air flow.

Well a shop would have added the correct charge with a "dial-a-gauge" weighed charging cylinder from a bulk cylinder.

Charging a unit using a liquid line sight glass would great when there is one, provided and only when the system is operating properly under a load. Just adding gas isn't always the problem. I hear ya on the over servicing. "If that much works, then this much is more better!"
I've seen the results of folks adding gas till the fusible plug blows.
Frosted lines on a medium temp application needs some esplain'in, it's not a walk-in freezer.
Seems the condenser & compressor have already been replaced. Perhaps we'll hear the rest of the story?

Safety first.

mackpeteno · 08-22-2016, 09:03 PM

Johndale,you are right about the bubbles in the sight glass.If you charge until the glass is clear it will be over charged.
As to R34 not having a glass,I would not buy a drier without a sightglass.I am having the same problem with not enough cooling.I just replaced expansion valve,drier and extensive vacuumn and it still doe's not cool right.
I do all of my own repairs and do not remember ever having this much trouble getting a unit to cool.
Doyle and Peggy,99 Country Coach-2013 Silverado 4x4.

Johndale · 08-23-2016, 05:30 AM

Quote:

Originally Posted by BFlinn181

I've not seen a glass 'window' sight gauge in a R-134a system except R-12 systems that were converted to R-134a.

They are there and most still have tape on the window painted black. I have run across a few aftermarket ones with no window and my 03 f53 has one and the tape was still on it.