2008 Explorer 4.0L AC compressor short cycle | Ford Explorer Forums - Serious Explorations

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2008 Explorer 4.0L AC compressor short cycle


Active Member
January 25, 2015
Reaction score
City, State
Oklahoma, OK
Year, Model & Trim Level
2017 Explorer Sport
2008 Ford Explorer 4.0L manual climate contol.

Wife was driving it the other day and the AC stopped working. Would blow hot air out of the vents then only 2 times it became cold like normal then went back to hot air coming from vents.

I checked the motors in the interior, the motor on the driver side is working and the passenger side is working also. When I turn the temp knob, I do get hot air when turned to warm.

It acted like the system was low on freon, the compressor at idle would cycle on and off every 3-5 seconds. The compressor wouldnt run long enough to allow cold air to come from the vents. So I bought one of those easy connect R134A cans and put a little freon in the system. The compressor short cycle became a little better and I was getting cold air from the vents.

However, I took it for a test drive and when the compressor would engage, the idle would drop low on the engine and you could see when the compressor would engage and dis-engage by looking at the tach and the feeling of the idle. Also, the mechanical fan was engaging more than I though it should. Sounded like a 18 wheeler. The temp outside at this time was only 75 degrees, so I don't think it should have been working that hard to keep it cool.

Fast forward to today, I was able to connect my AC gauge manifold set to the low and high sides. The gauges acted like the system was over filled with freon. I slowly evacuated the system to get the pressures back to somewhat normal, put some UV dye in the system and let it run for about 10 mins to check for leaks. During the 10 mins, the compressor cycle every 5-10 seconds at idle. I found no leaks in the system.

So I decided to completely evac the system and put a vacuum on it. I put a vacuum on the system for 30 mins and let it set with the vacuum off for 30 mins. The gauge needles did not move so I am pretty sure the system does not have a leak.

I found that the R-134a capacity of my system is 31 Oz.......I hope that is correct, was difficult to find.

So I recharged the system with one 18 oz can and one 12 oz can of freon....so that equal 30 ounces of freon.....so it should NOT be overfilled now. I also installed a new low pressure switch that was at the accumulator.

The compressor is still short cycling. The symptom is worse now, the compressor only stays on for 3-5 seconds. Won't stay on long enough to even start cooling the interior or get cold air out of the vents.

Here is a video of the gauges after I recharged the system (the temp outside was 70 degrees):

Here is a video of the compressor short cycling (the temp outside was 70 degrees):

Here is a picture of the gauges with the engine off:

What should I be looking for to fix the compressor and system so it does not short cycle and I can start getting cold air out of the vents.


Here is a pressure chart.

As stated above the temp is 75 degrees. so looking at the chart, 150-175 psi
at rest is right. Add more freon and stop the short cycle and the pressures will
be right on.