The Nissan Path

Really hot & humid yesterday. AC was working fine while driving. Then I hit a highway with frequent traffic lights, and I noticed that when stopped the vent air was getting warm & humid. Once I started moving again, the air would cool down.

When I got home, I let the truck run in drive and popped the hood to take a look. After sitting at idle for a few minutes, I saw that when the compressor engaged, it only did so for a second or two, then stopped.

I did recharge the AC a few weeks ago with an AC Pro D-I-Y kit. Could that have something to do with this?

Probably TOTALLY different, but my truck won't blow heat until you start driving it. The coolant temp will raise and the fans will eventually kick on. But until I actually start driving it, it won't blow even warm air out the heater vents.

Mine definitely doesn't cool as well if I'm not driving, but the AC does still work while stopped. Strange issue.

I've actually experienced your problem with heat not blowing warm until starting to drive. Turned out to be low coolant, so adding some to the tank solved that one.

Did you have issues of air in the coolant system? Did you need to add coolant to the radiator itself, or just the overflow bottle?

It was several years ago, so I don't quite remember. I think it was before I had my radiator replaced for a leak, so I think I just added to the overflow.
There was another occasion when I did "burp" the coolant system, but I don't think it was at the same time.

This is usually caused by insufficient cooling of the condenser, often because one of the fans is not working or there is blockage of air through the condenser core or the engine cooling system is running too hot, but, low refrigerant can cause this as well. I would start by making sure the electric fan is turning (and not turning too slow) when the A/C is on. Also, make sure the clutch fan is working, as well, and coolant level is good (the coolant gauge should be about halfway on the gauge. If those are good, the pressures should be checked to see if they are low, which would indicate a system leak. Generally speaking, the A/C system should never need refrigerant added to it unless there is a leak.

Thanks smj.
When I got home from work yesterday, I idled the truck in the driveway, and everything seemed OK - granted it was about 20 degrees cooler out than it was Sunday, but I don't recall the temp gauge going above half-way on Sunday.
When I turned the AC on yesterday, the electric fan did kick on, and I could hear it speed up after a few minutes (noticeably louder).
I guess I'll have to wait for another hot day to test out on the road. If it happens again, I'll go get the pressure properly checked. Using the gauge that came with the AC Pro can, the low pressure looks OK, but I have no idea about the high pressure.

Finally got the truck into the shop. The AC was overcharged. They evacuated over 2.2 pounds of refrigerant and refilled with the proper 1.54 pounds + dye to check for leaks. Everything is working great now.
I guess the gauge on the AC Pro can is basically junk. I would advise to leave those DIY recharge cans alone and pay the extra money to have a qualified shop do it the right way!

My AC just went out recently while we were out of town about 2.5 hours from home. Turned out something bounced off the road and hit my condenser. It cracked the aluminum and leaked out all the freon. The shop I took it to swapped condenser and recharged the system. Now my AC is blowing cold again.