OT question about A/C

[kid]

The valve might not close all the way by the cable or it leaks inside. Sounds reasonable as a cause.

Does the AC gauge read the same charge warmed up and running as it does static. We never fill Commercial or Residential units with out running them during the last part of the fill.

[71 LONG BED]

That is a very good thought fakename. Thank you. I'll check into that one, for sure. Ever since that dash was taken off I've noticed a few things were not quite right.

As far as needing more freon, it is right in the middle of the range it's suposed to be. How much more can it take?

[kid]

The gauge reads pressure. On a hot system there is more pressure than on a cold system. Fill it to the same pressure at night and the system will hold more Freon.

On commercial units it might say 5 lbs to fill from evacuated. Well we take the temp of the High pressure line and divide by the air temp entering the outside coil. We take the temp of the inside air and divide by the suction line temp. Then those two numbers are put into a supercool chart and our 5 lb system might need 7 lbs to be filled correctly. We are not looking for a book number but a corrected system fill number.

By the way filling it to the top edge of the blue area will not hurt it on a hot day.

[71 LONG BED]

Thanks Austin. I have determined that the cooling fan isn't coming on, so that may have something to do with it also. Unfortunately I haven't have any garage time at all lately. I hope things slow down when the baby is born. It just seems like there isn't enough time in the day for everything right now.
I will try to make time to try clamping off the heater hoses and I'll let you know what I come up with.

[71 LONG BED]

I checked right when my wife got the truck home from work last night. I figured I'd need to check it while it wasn't working properly and it was a very humid 90*+ day yesterday . I unplugged the sensor on the t-stat housing and the fan came on. So it's not the fan, maybe the sensor though, or maybe the truck just wasn't hot enough to kick the fan on. I also figured I'd try blocking the heater hoses. I clamped both, thinking that maybe the hose valve is bad and was feedeing hot air that was counter acting the cold. That wasn't it either. Then I checked the freeon charge. It was 120psi!! Then I realized the compresor wasn't kicking on at all.
I think I narrowed the problem down to the compressor failing to kick on after it's hot. My question now is, why would it stop kicking on after the truck is hot? You guys have been a big help so far, and I appreciate it very much.

[dablack00]

This is the point where I usually crack a book. Since the compressor does kick on and cools when the engine is cool, we know it works. We need to know what tells the compressor to come on. A real shop manual will have that info. A chiltons manual might. It might be that sensor in the thermostat housing. Maybe it is telling the fan that the engine isn't hot so the fan never comes on. On most aplications, the electric fan will come one when the AC is turned on, if the engine is hot or not. I just don't know w/ a jeep. If that sensor never tells the fan to come on, your AC is never going to get cold unless you are going 70 mph down the highway. Does this make sense? Does she experience this? Does the AC work ok on the highway, but not when she slows down?

Either way, I would get a book so you can really trouble shoot it.

Austin

[71 LONG BED]

It may be a combo of the sensor not working the fan, and a sensor that tells the compressor to turn on. I'm not sure if they are one and the same or not. I do see an electrical connection the runs from the low side line. A sensor maybe? If it's bad, it looks like I need a new line, which looks like I'd need to replace them both since they are on piece where they connect to the compressor. I've been told the auxiliary fan only comes on when the truck goes over 210*. I'll replace that sensor since it's prolly less than $20. I'll keep you posted. Thanks again.

[dablack00]

Hold on. before you start throwing parts at it, make sure that when you tested it that it didn't work correctly. Now you are telling me you have a mechanical fan and then this aux electric fan. How do you know if it was over 210? I too think you might have a combo of problems and that is why you need a book. To check that electric fan sensor, I would put cardboard in front of the radiator (if you can) and let the motor warm up. Keep the hood closed (it warms up faster that way). Then you will really know if the sensor is working or not. The book might even tell you an easier way.

The sensor on the line is too see if there is pressure in the system. If there isn't any pressure in the system on the low side, then you don't have enough freon and that sensor turns the compressor off. Maybe that sensor is bad and you have plenty of pressure, but the sensor doesn't think so. Again, a book might tell you how to test that pressure switch.

[71 LONG BED]

I don't think the truck can get to 210*. I put a 190* thermostate in it when I replaced the radiator. I have a chilton book at home, I guess I know what this weekends bathroom reading is gonna be.

[dablack00]

I bet with the card board in front of the radiator it will get to 210.

I don't get the bathroom scale thing? What are you going to do w/ a bathroom scale?

[kid]

The power from a system goes in the simple version from the on switch on the AC to the low pressure switch to a relay for van and compressor turn on. That way when the low pressure switch is making contact the fan and compressor can run. When the system is low the switch is open and the fan and compressor can not run so the compressor is not ruined.

The aux fan is the AC only Fan and might have a temp sensor after the Low side switch.

The low side will be closed and will read at the most 2 ohms between terminals if the system is charged and switch good.