2001 TJ A/C Clutch Cycling On/Off. System Charged. Any Suggestions - Jeep Wrangler Forum
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Old 06-25-2012, 01:59 PM   #1
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2001 TJ A/C Clutch Cycling On/Off. System Charged. Any Suggestions

Hello All!

I have read through many posts and cannot find one that could help. My system is charged. Before the compressor kicks on the gauge I have is showing system pressure at about 50psi. When the compressor turns on the pressure drops to about 15psi. I understand this is normal, however the clutch will engage for about 2 seconds and then disengage for about 2 seconds. (does this constantly)

I could understand that it might be low on Freon but the system is charged.........very confusing. I changed the clutch relay thinking that might be the issue but it was not.

Any help would be great! This might sound dumb but I also have to put in a new bower motor resistor since I only have no....or very fast blower speed. would this effect that A/C in any way?

Thanks

Joe

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Old 06-25-2012, 03:02 PM   #2
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if you are sure that the system is fully charged then it sounds like you probably have a bad pressure switch. i don't know what a jeeps operating pressure should be so i can not give guidance on that.

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Old 06-25-2012, 03:02 PM   #3
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Just changed the BMR so now my heater control works. After speaking with my father, we think it may be over charged even thought my handy dandy gauge says otherwise.
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Old 06-25-2012, 03:03 PM   #4
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yeah thats what I was thinking........I have to find out what pressure it operates at because all vehicles are different
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Old 06-25-2012, 05:34 PM   #5
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There are 2 possibilities for low side readings that I know of. 1 is low refrigerant & 2 a blockage in the system. You will need a hi side gauge to see a blockage. A blockage will cause the lo side to fall & the hi side to climb pretty fast. If only the lo side is dropping with below normal hi readings then the refrigerant is low.

Here is the FSM lo side pressure cut out:

The low pressure cycling clutch switch contacts are open when the suction pressure is approximately 141 kPa (20.5 psi) or lower. The switch contacts will close when the suction pressure rises to approximately 234 to 262 kPa (34 to 38 psi) or above.

Then this:

Rapid compressor clutch cycling (ten or more cycles per minute).
1. Low refrigerant system charge.

The low side pressure is too low, and the high side pressure is too high.
1. Restricted refrigerant flow through the refrigerant lines.
2. Restricted refrigerant flow through the fixed orifice tube.
3. Restricted refrigerant flow through the condenser.
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Old 05-15-2013, 05:36 PM   #6
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Quote:
Originally Posted by Wick3442 View Post
Hello All!

I have read through many posts and cannot find one that could help. My system is charged. Before the compressor kicks on the gauge I have is showing system pressure at about 50psi. When the compressor turns on the pressure drops to about 15psi. I understand this is normal, however the clutch will engage for about 2 seconds and then disengage for about 2 seconds. (does this constantly)

I could understand that it might be low on Freon but the system is charged.........very confusing. I changed the clutch relay thinking that might be the issue but it was not.

Any help would be great! This might sound dumb but I also have to put in a new bower motor resistor since I only have no....or very fast blower speed. would this effect that A/C in any way?

Thanks

Joe
Joe, Not sure if you fixed this as I do see the post is almost a year old. I had the exact same prob. I followed this for the service manual. Step 6 below stopped the compressor from cycling and the PSI on the low side was at 10ish. So I charged it to 50 psi and it blew cold. Plugged in the wire harness back in and she works perfect.

24 - 10 HEATING AND AIR CONDITIONING TJ DIAGNOSIS AND TESTING (Continued)




(3) Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged.
(4) The engine should be at operating temperature. The doors and windows must be open.
(5) Insert a thermometer in the driver side center A/C (panel) outlet. Operate the engine for five min- utes.
(6) The compressor clutch may cycle, depending upon the ambient temperature and humidity. If the clutch cycles, unplug the low pressure cycling clutch switch wire harness connector from the switch located on the accumulator (Fig. 6). Place a jumper wire across the terminals of the low pressure cycling clutch switch wire harness connector.
(7) With the compressor clutch engaged, record the discharge air temperature and the compressor dis- charge pressure.
(8) Compare the discharge air temperature to the Performance Temperature and Pressure chart. If the discharge air temperature is high, see Refrigerant System Leaks and Refrigerant System Charge in this group.

Fig. 6 Low Pressure Cycling Clutch Switch - Typical


1 – LOW PRESSURE CYCLING CLUTCH SWITCH 2 – ACCUMULATOR






Performance Temperature and Pressure








Ambient Air Temperature
Air Temperature at Center Panel Outlet
Evaporator Inlet Pressure at Charge Port
Compressor Discharge Pressure

21° C (70° F)
-3 to 3° C (27 to 38° F)
179 to 241 kPa (26 to 35 psi)
1240 to 1655 kPa (180 to 240 psi)

27° C (80° F)
1 to 7° C (33 to 44° F)
221 to 283 kPa
(32 to 41 psi)

1380 to 1790 kPa (200 to 260 psi)

32° C (90° F)
3 to 9° C (37 to 48° F)
262 to 324 kPa
(38 to 47 psi)

1720 to 2070 kPa (250 to 300 psi)

38° C (100° F)
6 to 13° C (43 to 55° F)
303 to 365 kPa
(44 to 53 psi)

1860 to 2345 kPa (270 to 340 psi)

43° C (110° F)
10 to 18° C (50 to 64° F)
345 to 414 kPa (50 to 60 psi)
2070 to 2690 kPa
(300 to 390 psi)

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