Hey guys. So my A/C had been getting a little tired. I know I have a leak somewhere because I had to fill the system up at the beginning of last summer. Anyway, I went down and got a can of A/C Pro from advance auto and filled her up according to the instructions. However, doing so didnt seem to help the air get any colder. Afterwards, I noticed that my compressor is short cycling. It turns on and off every few seconds, with no pattern. Im not sure if it was doing so before I put the new freon in, but I feel like I would have noticed if it was. It also is kind of groaning when it turns on but that might be normal (not really sure what it is supposed to sound like). Before I add more freon or take it to get looked at, I wanted to see what you fine people had to say. Any help would be much appreciated.

 

When you were, following the directions, how high did you allow the low pressure to get? Should be no more the 45 to 50 pounds in this weather.

 

With the compressor running i filled it to 50 lbs (higher when the compressor was off). Now when the compressor turns on it begins to drop but then shuts off before it hits the 45 to 50lb range. This continues without a pattern that i can decipher. It is at about 75lbs without the running compressor

 

I have an update. I let the truck sit for about two hours. Then i checked the readings again. This time the compressor stayed on and the pressure was around 35 psi. The air in the truck got really cold (hand numbing cold). So i said let me go for a short drive. As i drove i felt the air getting a little less cold (may have been my imagination). When i got back (5 min spin) i opened the hood and the ccompressor was cycling like before .... every few seconds. As i read online, compressor cycling could be the result of low freon and i was only pulling 35 lbs. Should i add more? I have put about 15 ounces so far.

 

No, not without a proper 2 gauge set so you can determine what is wrong, as it stands, I wouldn't run it any more if it were mine till you can have a good a/c guys check it out.

 

Ok Mike. I called a local Autozone and they are getting me a set of Manifold Guages which will be in tomorrow morning. I will get back to you with the readings. Any tips on using it? I watched some videos regarding how to use them but I dont want to miss some Land Rover specific. Thanks

 

It has been too long since I used them, really can't help.
Let us know what you find.

 

Nothing land rover specific. Low side hose (blue on the manifold set) goes to the port where you connected the "freon" can. High side hose (red on the manifold set) goes on the other port. The High side port is larger than the low side. It's "dummy proof" no pun intended.

When checking pressures have another person or get creative with the throttle and bring the engine RPMs up to 2,000.

You high side reading should not breach 250-275lbs on a 85-90 degree day.


Report back when you get the Gage's and Gives us ambient outdoor temp. High pressure, Low pressure, Outlet air temps (put a meat thermometer in the air vent).

 

So I have an update. As it turns out, after going to autozone and waiting for an hour for the delivery to arrive this morning, they don't rent the manifold guages (the kid behind the counter got it wrong). So, I politely asked to buy one and they were out of stock.... he never put the order in (pretty ticked). Anyway, as it turns out, I will be getting one from Harbor Frieght sometime this week. To salvage some of my time, I did manage to do my own test while waiting around with the simple low side guage that I have. Here's what I found:
1) Car at idle in 83 degree weather with a/c on max had a pretty constant pressure of 38 (would fluctuate about 2 in either direction but I would say more constant than not. No short cycling (compressor running constantly), aux fan running as it should, low side a/c hose cool/cold to the touch, high side a/c hose hot to touch (not scalding as I could keep my hand on it)
2) During idling the temp got cold in the cabin. Not sure on the actual temp because my meat thermometer doesn't have numbers below 75, but I would say somewhere between 45 and 50 (nice and chilly).
3) I let it run like this for probably 10-15 minutes and everything was fine.
4) I then had the misses jump in the driver's seat and raise the rpms to 2000 while I watched the guage. As she hit the gas I watched the needle raise to about 41 and then the compressor went into its short cycling mode. It would switch on and off every few seconds with no pattern it seemed. Also, this continued even after we let the rpms drop down to idle. I turned off the truck at that point and didnt touch it.
So, I know you guys are probably going to say I need the readings from the manifold guages but does this information shed any light on what could be wrong. I've been reading about a high pressure switch that may be faulty. I'm just worried as I know a/c systems can be expensive and I dont really have the benjamins for it right now ..... a/c isnt a necessity I guess

 

I had the short cycle issue after just adding a little from the ac pro set. I ended up stopping by a local Goodyear shop. $50 they hooked it to their machine that vacuum test and then fills to the correct levels. Works perfect now. I would suggest seeing if anywhere around you does this.