AC woes

[Chuck W]

I ask, because it may be possible that the schrader valve isn't opening up, allowing refrigerant in.

[Magnetic82]

I used Murray brand high and low pressure ports as suggested from above. They seem to be fine. I replaced the lines with Four Seasons parts. And the gauge manifold is from Harbor Freight. I used a Motorcraft reseal kit to reseal the compressor which went well. I may need to jump the pressure switch for a little longer than before but won't be able to try again for another week. The shop that is rebuilding the starter is a week behind. By the time I make any progress on this there will be snow on the ground. That's my luck.

[Chuck W]

Well, I would make sure that the connectors/fittings are actually opening the valve. I've run into that before.

[Magnetic82]

I'll double check the connections whenever I get the thing running. Ran into another problem.
I received the rebuilt starter back but think it might be a replacement. Didn't look close enough when I removed it but now there is a projection near the upper bolt mounting surface/ hole that won't allow tightening of the bolt beyond maybe halfway. Simply can't get a socket over the bolt. I have no idea how I removed the thing. So after three hours of sweat, pain, and cursing its back off and ready for the grinder. What a PITA! The website won't allow me to upload a photo but if you have ever seen these starters it should be obvious. I know this is an AC thread but a photo of an original starter showing the upper bolt hole would be nice. I thought I had thin wall sockets but either I don't- I tried four of them- or this metal projection needs to go.
As usual this is taking way too long. But that's my luck.
Cheers.

[KevinK]

AC systems are usually pretty simple but some small problems can bring things to a halt. You want to evacuate the system first. This does 2 things. First you can leak check the system by watching it leak up under vacuum. You could leak check by pressurizing it but that get tricky. So pump it out and monitor the vacuum for an hour or two. The other benefit of evacuating the system is to remove contaminates such as air. Air contains moisture and that moisture will form ice inside. Ice will create a blockage and pop the pressure relief valve, out goes your Freon as well. This is a safety feature. If you still have Freon pressure in your system then there is no need to evacuate the system just to top it off.

There are 2 switches on the must ac system to allow it to turn on. There is a wide open cut out and a low pressure cut out. The low pressure cut out is what keeps the compressor from coming on when low on Freon. By jumpering the switch, the system will suck out Freon from the low side to maintain pressure on the high side. The new can of Freon has only so much pressure and is a liquid in the can. The ac system creates much higher pressure on the high side, so much pressure it would blow up the can. The cans have a blow out provision. This is why we charge from the low side. Professionals fill with liquid from the high side and it goes much quicker. Filling from the low side with the low pressure switch jumpered my take a while, 30-45 minutes. Once you get some Freon in the system, you can reconnect the low pressure switch but it will continue to cycle on and off as the pressure drops (low side runs out of Freon). It will take much longer to fill with it cycling on and off.

As the system fills with Freon, the temperate at the vent will decrease. 32 degrees is pretty low but 40 is not bad. If the system is over filled, the temp will increase at the vent. There are some charts which show relationships between pressures, exterior temps and cooling temps. You will not get the lowest vent temp on a 120 degree day. Also remember the system is designed to work going down the road and not so much at an idle with limited air flow. When checking the inside temp, close all vents except for 1, set to blow out a dash vent, set to max ac. Now you can put a temp probe in the Mac vent.

You will find systems low on Freon will cycle on and off quite a bit. You can see the compressor clutch engage for like 10-15 seconds and the go off. This is due to the low pressure switch opening. Once the cycling time gets up to about 60 seconds, you will see the vent temp drop. In an ideal world, the low pressure switch will not cut out the compressor due to low pressure and the compressor will continue to run continuously. The constant cycling on and off will eventually wear out the clutch.

[Magnetic82]

Great info. I'll try again once the car is running. But now it isn't. I managed to replace the starter and the relay but nothing. Just the fuel pump running and then one click and the oil light comes on and I've had it for a while. So when the car decides to work, I can address the ac issue. Like I mentioned. Snow will be on the ground first before this terd runs.
Oh well. Makes life interesting.
M