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Compressor short cycle

ldr on Sat October 20, 2007 10:50 PM User is offlineView users profile

Year: 89
Make: Mercury
Model: Cougar XR/7 SC
Engine Size: 3.8
Refrigerant Type: R134
Ambient Temp: 85 F
Pressure Low: 35
Pressure High: 190
Country of Origin: United States

I just converted to 134. The accumulator is new,cycle switch new,and orifice tube/line new and all the seals replaced. I flushed the system and flushed the compressor with oil. I added 6 oz of oil in the system and vac for 45 minutes. It stayed at 29 inches for another 30 minutes after vac. After adding 30 oz of 134, it cycles on about every 8 seconds. It will go to 35 on the low side and 190 on the high and cycle off. When the low reaches about 50 , it will come back on for about 3 seconds then off. There is no cool air at the vents on any blower speed. The vent doors are working properly. I'm sure I have something screwed up and would appreciate any help. You guys have been very helpful in the past.
Larry

Chick on Sun October 21, 2007 4:13 AM User is offlineView users profile

What was the reason you retrofitted in the first place? Did you change the ciompressor or use the old one? Check the clutch gap first, check the coil for three to four ohms also..If it's cycling off at 35psi, that is to high, should be betwqeen 19 and 22 psi on those.. So if the clutch gap and coil are fine, change the cycling switch...Even try your old one..Not uncommon to get a bad one right out of the box

The 3 second drop on the low side is a concern though..Could have a blocked condenser, low charge etc.. Let us know everything you did, and if adding a few more ounces stops the short cycling after you get a new/used switch...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Sun October 21, 2007 at 4:18 AM by Chick

ldr on Sun October 21, 2007 9:05 PM User is offlineView users profile

went out this morning and checked the clutch gap (.018) and coil (slightly less than 4 ohms). The system was at 95 on the pressure gages static and air temp 84 F. I started the system and ran at 2000 rpm for about 3 minutes. The system was cooling at the vents. I seemed to be cycling coming on at about 45 and going down to 25 before cycling off. High side going up to about 160 .I added about 2 ounces of 134 and seemed to get worse. The compressor came off another car I had wrecked. It had 134 system and was working very well at the time of the accident. I let the car set a while and came back to run it but, The electrical system is completely dead. The Car has a battery 2 months old. I am getting power past the fusible links, but absolutely nothing works. I will have to delay more trouble shooting on the AC until I can figure this electrical problem out.

Chick on Sun October 21, 2007 10:43 PM User is offlineView users profile

Those pressures indicate a low charge. I would recover the refrigerant, pull a deep vacuum and recharge the full amount back in.. After you fix the electrical problem you might want to try that.. make sure no air is in the system when you recharge it..Hope this helps..

PS: Clutch gap is fine, and so is the coil ohms..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

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