My air conditioner doesn't seem to get cool enough. I put the guages on and it has 40 lb on the low side and 200 on the high. the air get to 60 degrees when the outside temp is 75. Would appreciate any help on where to start to look. The heater hoses feel cool so I think its not coming from the heater side.

This is the time of the year (Max Temp, Max Humidity) that really tax our air conditioners, but in PA?. That being said, an air conditioner that is functioning properly will drop the temperature of the incoming air by about 18 degrees, I prefer 20 but sometimes that is not attainable.

Your pressures seem OK & your heater hoses are cold so good there. Check the condenser surface make sure it isn't dirty or restricted in any way. If it is, use air, not water, and blow it clean. Make sure that the condenser cooling fans in front of the radiator (gas Models) or at the condenser (Diesel Models) are on when the AC is on. The diesel fans run anytime the AC compressor is switched on, the gassers use a pressure switch on the receiver/drier to switch them on at a preset pressure. You can disconnect that switch and jump it to test the fans, circuit & relay. NOTE - Your high-side pressures are not high enough at 200 PSI to cause an issue so the next steps are probably what you are after.


Note that I said "Incoming Air" make sure your A/C control is set on max and make sure the max air door is closing! That alone will cause AC air temp at the register to rise 20 degrees down here in Cajun Country. Now, Most vacuum leaks occur in the, usually blue, vacuum line that is routed to the max air (recirculate) door actuator. Check it by opening the hood, locate the evaporator housing on your left and the small, about golf-ball sized, actuator at the bottom. Confirm operation by having someone switch between normal and Max AC. If it does not move, unplug the actuator and connect a Mighty-Vac hand vacuum pump and draw it down yourself. If the door closes, the problem is probably in the vacuum supply. Trace the 1/8" vacuum line back, through the bulkhead, we can't say firewall anymore, all the way back to the AC control & check for leaks. If there are no leaks confirm vacuum to the control is present follow the usually black vacuum line back through the bulkhead to the vacuum reservoir, usually round about the size of a softball, from there trace it back to the engines intake manifold if gas powered or vacuum generator if diesel. When ours failed it turned out to be the control itself which I located at a salvage yard from an old Dodge Pickup Truck.

Good Luck

I have found on some trucks that they use a cab filter and that'll restrict the air flow volume. Don't know if you have such a filter on your Barth.

My first inclination is the condensor is dirty. Clean it real good at the car wash from the backside if possible. I think the ratios should be closer to 1 to 2 not 1-5.

Is your's an old R12 system?

Cleaning the condenser is a good idea - but it's hard to get to.

As BillyT mentioned, check the inside air door. It should close (which will open the inside return). The blue plastic vacuum line to my coach's actuator was entirely detriorated.

Assuming you have R-134a (It helps to have your coach model and year in you sig so we can guess more reliably), your pressure differential is a little off. Better would be 30/250.

This could be a worn compressor, but the first thing I'd suspect would be the expansion valve.

This is in a 92 Breakaway with a Cummins. I blowed the condenser out got a little dust and the fans work.The door seems to be working. you can hear the blower and feel it pulling air from the inside. It has 134 freon. if more freon was added would it change the pressure to get closeer to the 30/250 that Rusty mentioned. and if you change dryer and expansion valve would you loose freon? Like I said I know enough about air conditioners to be dangerous The original owner told me he never used the c.air

Changing the dryer and/or the expansion valve require evacuating the system.

Adding R-134a should increase suction (and discharge) pressure.

The output air temp should be measured at the vent closest to the HVAC blower (passenger side, usually).

Also check the expansion valve (it's at the entrance to the evaporator chamber) for icing. It should be cold but not icy; the expansion valve is designed to keep the evaporator temp above 32°F so the evaporator won't ice up and restrict air flow.

It's very hard to diagnose many issues remotely, but there are some more things you can do before having to take it in to the shop.

The next test is to check the high pressure calibration of the hi-lo switch (usually located at the receiver-dryer). With the engine and A/C on, watch the compressor clutch to see if it is engaging and disengaging more frequently than several minutes. If it short cycles, suspect the hi-lo switch cutting out at too low a pressure. That can be changed without evacuating the system because it has a Schrader valve (in most cases - some techs remove them, so use caution).

A tricky way to check the compressor is to disconnect the condenser fans. There should be a connector at the hi-lo switch. With the engine off and IGN and A/C on, pull the connectors to see which one stops the fan.

NOTE: For the next step, have the gauges in view from the driver's seat, or have a helper ready to shut the engine off - VERY IMPORTANT! This step will test the compressor, expansion valve, and the hi-lo switch (again), but it can cause overpressure if the hi-lo switch fails.

With the guages connected, start the engine. If the compressor reaches 300 psi, STOP the engine, and the compressor checks out OK, but the high pressure cutout of the hi-lo switch is too high. Note the low pressure reading. Because the evaporator is warm and the condenser isn't providing much cooling, the expansion valve should go to minimum reading (lowest suction pressure); hopefully this will be less than 40 psi.

Don't forget to reconnect the condenser fan.

A final possibility is that there is too much oil in the system.

Anyway, if the compressor doesn't gain discharge pressure or the expansion valve doesn't produce lower suction pressure, it's time to see a tech. Write down what you have done. Expect to pay for evacuation, flush, new R-134a, and replacing of the receiver-dryer in addition to other repairs.

Back to trying to get the chassis air to work, went to NAPA with the dryer and the pressure switch located next to the dryer and they couldn;t match up. Would appreciate any numbers anybody could give or ways to find pressure needed.My other half insist the the air has to work for going down the road...Also does anybody know the part number for the fanbelt for a Breakaway with a Cummins with saparate belts for the airconditioner

I got ours working. Replaced the expansion valve and the dryer and changed to 134 because of availability. All up and running and the compressor desided to retire.

The temp drop runs from high 20s in the desert to about 15 here in KY. The a/c serves two purposes. First it is a dehumidifier and then an air cooler. With this high humidity much of the capacity is used to dry the air and what is left over cools it. But yes it was worth it. Don't need to run the roof air until it gets in the high 90s.

I have completely replaced the "c" air system because I want it to work! First, you probably have an evaporator (a second ac and heater unit) in the bedroom area. You should have a switch that says Aux Heat on the side dash area. This is the fan for the bedroom and it must always be on(it is a three position switch of-lo-hi) when the ac is running. If not it will freeze up and the system will not work properly. That will restrict freon flow giving you the 60 degree air and the higher than ideal low side pressure. It should be about 32 on the low and 220 + on the high. The dryer is not majic, size does not matter, just the proper connections - male to male or male to female. In our coaches any size is easily installed. The recommended interval for changing it is every time it is opened or every two years. The expansion valves (two of them, remember) should also be changed. You must be sure the sensor bulb of the expansion valve is tightly fixed to the high pressure line as close to the evaporator as possible. Wrap this with the Tacky Tape sold by auto ac distributors. Leave no opening to free air. The bulb has be completely isolated to the freon line only. Replace all the O rings with proper R134a GREEN rings. You can forget the sight glass because with R134 and the long lines you can never get it to be fully liquid. Evacuate for at least 1 hour or until you get 28.5" of vacuum. Your dash air temp should be low 50's and that is possible if everythhing else is working. I sealed the outside air closed so it runs on MAX all the time. It does not hurt to install manual valves on BOTH units. That way it is only an ac system in the summer and you can open them in the winter. I get 32 psi low, 235 high, with 52 degree air at 1000 rpm, sitting in the driveway with outside temp of 97 and 78% humidity. I think your problem is the second unit or leaking hoses. My originals were connected to fittings with screw type band clamps. I replaced them all with crimped hydraulic fittings.

G.C is there a chance that you could give me the number of the dryer and expansion valve the you installed? As I said NAPA wasn't able to find anything to fit.I know that the hi-low pressure switch is bad and there is no number on this either,so I need this# also. I did look at the aux heater to see if there was a evaporator there could only find heater core only.

Don't have the numbers available as they are many states away. Anyway I pulled the dryer and took it to NAPA and got one that hooked up the same way and was about the right size although I don't think it makes much difference. As to the expansion valve, I removed mine and went to Ebay and found a universal unit that looked like mine.

quote:

Originally posted by Gary Carter:
I got ours working. Replaced the expansion valve and the dryer and changed to 134 because of availability. All up and running and the compressor desided to retire.

The temp drop runs from high 20s in the desert to about 15 here in KY. The a/c serves two purposes. First it is a dehumidifier and then an air cooler. With this high humidity much of the capacity is used to dry the air and what is left over cools it. But yes it was worth it. Don't need to run the roof air until it gets in the high 90s.

Gary did you change directly from Freon 12 to 134a ?wally 34ft monarch van-isle.

If changing from R12 to R134 you need to do the following.

Change the dryer
Drain the compressor oil.
There are two types of oil. One is PAG and the other is ester. I used the ester as it will mix with any left over R!2.
Evacuate the system by pulling a deep vacuum. Refill and go.

Just a note on the oil I believe I have the types rite. Check the cans to be sure.

Note 2: If you have a functioning R12 system keep it.