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Another one for AC buffs

O

Olliejunkie

Well-known Member
Charged up my AC this morning. Compressor cycles 15-30 seconds unless the cab fan is high. Getting 45 degrees at vent but doesn't seem to cool the cab as much as I think it should. It's a 93 f350. New pump, accumulator and orcice (red). It converted it from r12 to 134. Specs I found said 44oz. I put approx 85 percent as I read. Is it normal for it to cycle if the fan isn't on high?
 
That sounds about right.

The purpose of the cycling switch is to prevent freezing the coil.

If the return line is sweaty cold, it's good.

Possibly the evap coil is clogged externally, or there may be a cab air filter that needs replacing. Not sure how to get to the coil to clean it, maybe through the blower motor hole, just guessing.
 
Thanks Steve. I'm guessing it needs cleaned too. No cab filter. I did clean it once through the blower motor trying to get more heat but Im sure I didn't get it all. Guess it's time to try again. Damn mice. Thanks for confirming my thoughts. AC I'd new to me.
 

On the low side at what pressure did it cycle..

I think you are leaving a bunch of information out try again no charge for information...
 
(quoted from post at 19:14:27 08/05/18)
On the low side at what pressure did it cycle..

I think you are leaving a bunch of information out try again no charge for information...
Click to expand...
Not sure. It was 40 psi low and 150 psi high when it was pumping.
I took the evaporator out. The mice had it pretty plugged up. Will hopefully get it together in the morning and see how it does then.
 
(quoted from post at 22:14:27 08/05/18)
On the low side at what pressure did it cycle..

I think you are leaving a bunch of information out try again no charge for information...
Click to expand...
hat about that 44 ounces?
 
R 134 reaches 32 degrees F at about 20 psi. If your pressure cycling switch is adjustable, a lot of Fords were, set it to cut out at 21 psi. You may have to disconnect the evap fan in order to for the pressure to get that low. R12 cuts out around 28 psi, if I remember correctly. If your switch is not adjustable, just get one already for R134.

Garry
 
When the charge is correct, the refrigerant is just finished evaporating as it leaves the evaporator coil. As Steve said, the return line (the larger of the two) should be sweaty cold. If it stays cold too far on the way back to the compressor, the system is overcharged. If it is not cool enough to cause condensation, the system is undercharged. Saves a lot of arithmetic.
 
I know it was sweaty and not freezing. 44 oz is what it called for in r12. Conversion said to put 85 percent.
 
(quoted from post at 19:56:28 08/05/18) R 134 reaches 32 degrees F at about 20 psi. If your pressure cycling switch is adjustable, a lot of Fords were, set it to cut out at 21 psi. You may have to disconnect the evap fan in order to for the pressure to get that low. R12 cuts out around 28 psi, if I remember correctly. If your switch is not adjustable, just get one already for R134.

Garry
Click to expand...
Thank you. My switch is not adjustable. The one I put on may be for R12. I will check on one for 134
 
(quoted from post at 20:21:38 08/05/18) When the charge is correct, the refrigerant is just finished evaporating as it leaves the evaporator coil. As Steve said, the return line (the larger of the two) should be sweaty cold. If it stays cold too far on the way back to the compressor, the system is overcharged. If it is not cool enough to cause condensation, the system is undercharged. Saves a lot of arithmetic.
Click to expand...
It is sweaty all the way back to the pump. I cleaned the evaporator out and that helped a bunch.
As far as my heater fan goes I think it is only working on high so no air movement on other settings. Tomorrow's project. I'm guessing the dohicky burned out. Can't remember what it's called. Time for some research.
Thanks for all the help.
 
(quoted from post at 17:43:06 08/06/18)
(quoted from post at 19:56:28 08/05/18) R 134 reaches 32 degrees F at about 20 psi. If your pressure cycling switch is adjustable, a lot of Fords were, set it to cut out at 21 psi. You may have to disconnect the evap fan in order to for the pressure to get that low. R12 cuts out around 28 psi, if I remember correctly. If your switch is not adjustable, just get one already for R134.

Garry
Click to expand...
Thank you. My switch is not adjustable. The one I put on may be for R12. I will check on one for 134
Click to expand...

Bought a new fan resistor and pressure switch for r134. Seems to be working good now.
The switch for R12 is 45/25. The r134 is 53/25 so a bit different. I think the new resistor is probably what fixed it.
Thank you for all the help. Now for my Taurus. I think it just needs the clutch adjusted but it's a major job.
 
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