I have a 1996 E150 conversion van that I'm looking for a little guidance with. We don't use it for daily commuting but it is our vehicle of choice for all our family outings and any extended trips. The AC was working fine the last time we had the need to use it, which was about a month and a half ago(it's been a rather cool and rainy summer so far). This past weekend we were heading out for an outing and the AC was only blowing out hot air only. Thinking the freon 134 might be low, I stopped at a local store and bought a recharge kit with a built in gage. Following the instructions I tried to recharge the system to the normal levels. In the process I noticed the the compressor was cycling on and off. I'd guess 2 seconds on and 10 seconds off repeatedly. The system was low and I added the 134 until I was in the normal pressure range. As the compressor cycled on, the needle would dip to the low side of the normal pressure range and then as it cycled off the needle would spike to the high end of the normal range. Not wanting to over pressurize the system I stopped adding the 134 at this point, but the compressor continued to cycle on and off and only blow hot air. I read a similar thread in the archives where the solution seemed to be that recharging the system would get the compressor to cycle normally. My thoughts are that when the compressor does cycle on, the pressure drops to the low end of the normal zone and that maybe it is not enough pressure to deactivate the low pressure switch on the compressor, so it cycles off. I'd add more 134, but I'd like some confirmation or advice before doing so. Thanks for any thoughts in this matter.

 

Yup. Probably still undercharged. It should stay on almost continuously at idle. The guage doesn't happen to have pressures on it to correspond with the Normal/Not Normal "dummy scale", does it?