fixed my a/c

[iviper123]

i replaced my condenser, drier and lines today vacumed it out and refilled it.

my compresor is always running, its that normal? i couldnt get any new switches by today but will replace them soon as i get them, and the wires to my comp clutch are going bad i think if i play with them the comp will tutn off and on depending on how i move them... does anyone know what the pressure reading should be for the ac system

 

[robzombie4551]

38/40 Lbs. on the low side when running at about 80*/90* And about 100/110Lbs. on the high side. You should check both to see if you have a blockage in the system. If both readings are low you need more R134. If readings Are close you have a faulty high/low pressure switch. Hope this helps.

 

[matuva]

are you on defrost position ? with air stream going to the windscreen ?

 

[mitchedo]

At 90 degrees ambient, the high side should be closer to 250. If both readings are low, and the temp from the vents is not cold, then you need more R-134. If both readings are close -- and the low is too high, it's likely because you forgot to install the orifice tube -- or the compressor is shot. The high pressure cut-out only shuts off the compressor when the high pressure goes beyond safe limits -- somewhere near 400 psi. The low-pressure switch is responsible for cycling the compressor to prevent freeze-up of the evaporator. It should cycle the compressor off at about 35-ish psi or so; it should cycle the compressor back on somewhere south of 50-60 psi.

The low pressure side is what gives you cold air. The ideal system keeps the low side as low as possible without freezing the evaporator. I can't remember the temp/pressure chart for R-134, but it seems that 35 psi relates to about 35 degrees F.

If I don't charge a system by weight, I charge by the high side mostly. I put in refrigerant with the pressure/temperature chart in mind. I load the system until the high side is at its maximum for the ambient temperature. The higher the ambient temp, the higher the high side will go. You don't want it to go over 350 on the hottest day. You also don't want to put in so much R-134 that the low side won't pump down to a cool pressure. Also, if your high side won't pump up, and your low side won't pump down, then you either forgot the orifice tube or your compressor is weak.

 

[iviper123]

well the ac works it gets colder the higher the rpms. my pressure at idle run at about 250/65 or so and stays there and the clutch does not shut off.

i replaced the low side switch. i put about 30oz colont and 3 ounces oil in it when i charged it. the old drier said to charge it with 2lbs of coolant.

 

[WarWagon]

You say it is fixed. If it is blowing cold air then yes it is.

I agree with mitchedo on pressures. I disagree on charging by pressure -don't do it. You have to charge these systems by weight from a vacuum. Charging the system by pressure makes you 12 oz or more short of freon. That last can by weight will not change the pressures of the system at all, but, has everything to do with flooding the evaporator for max designed cooling and bringing oil to the compressor.

The Cycling Clutch Orface Tube system will only kick out the clutch to prevent evaporator freeze up or high side overpressure. Pressures are nice, but, a good gauge set will have temperatures next to the pressures and read around 40 degrees for the clutch to kick out. You have problems if revving the engine brings it below 35 degrees. Pressure = temperature of the freon and nothing else. Aside of diagnostics that is. Not for determining the state of charge in this system design.

Set your blower fan on low and rev up the engine to 1500 RPM - do not do this very long!!! The clutch should cycle out in under 20 seconds - when the pressure temp of the evaporator gets around 40 degrees F. The clutch on a properly charged system will not kick off with the blower on high and idle. (unless it is really cold out) The clutch cycling at idle means there is very little freon in the system - 1/3 charge or less.

How did you get 30oz? That 2 oz shy, but ok.

Did you clean/replace the orface tube?

How about a fan clutch checkup and radiator/condenser/oil cooler cleaning? Cooling the condenser has a lot to do with good cold AC.

 

[WarWagon]

Moving the wires and kicking out the clutch is a problem. Weak voltage due to bad wires or connection will slip and burn out the clutch.

Is it the connector at the compressor or elsewhere that movement kicks the clutch out?

Connector? Possible cracked coil side connector and wire. Anywhere else? Get a new harness repair splice with connector - unless you can isolate the section of wire. There is an inline diode in some AC wiring: Like 1993 has it about where the center manifold bolts are for the heater hose in the AC harness. Check this area for issues as well. Always dissemble the ground and check it esp with this issue.