1985 mustang gt factory a/c questions

[kfxmatt]

My 85 has factory air.i tried it the other day and realized that it isn’t kicking on.im sure it’s either empty or low on r12.i had ordered a set of guages and a few cans of r12 from eBay.does anybody have any advice on what I need to do to properly recharge this?hoping this is the reason it’s not kickin on.otherwise I’ll dig deeper.but it’s a good starting point.i would be great if it worked again

[KevinK]

You can start with checking the static pressure or jumper in the pressure switch on the filter dryer up by the firewall. If it engages then it’s probably low or you have a leak.

[KevinVarnes]

As Kevin stated, start with the static pressure. If that looks good then check for 12V at the compressor clutch coil. If nothing then check the low pressure switch for continuity. If there is adequate system pressure and the sensor is working properly it should be closed (little to no resistance). Any idea how long it has been since it functioned properly? Just my opinion,but depending on the condition of the system I would guess low system pressure due to a leak. I'd make sure the system is secure before adding more R-12 otherwise it is just going to float away. Depending on cost/age it might not be a bad idea to just replace any seals and hoses that you can and pull a vacuum on the system. It should be able to hold that vacuum unless it has leaks. I'm not a big fan of filling to a pressure, but sometimes people don't want to pay to have a leak diagnosed and fixed so you do what you have to do.

[erratic50]

Glow PAG oil works a treat for finding future leaks. Picture of our 96F250 AC leak dianosis

By far the most common place for leaks is the AC lines to the condenser that’s mounted in front of the radiator.

Best bet is replace the O rings there then go to NAPA and get the repair clamps for them. I was killing seals every 90-120K miles. Last time around I did a redo was in 1998. Those held up the remaining 290,000 or so miles my 86 has went. Picture of the kit attached. You need two and they are different sizes. I don’t remember which sizes I needed anymore but their book should tell you.

You can convert to R134A if you want. Conversion oils are compatible with both and work a treat. Not mandatory — I ran the R12 switch for years and years but there is a low pressure switch available that causes your system to run the higher R134A pressures and cool a bit better.

[kfxmatt]

Man! Thx guys! I will dig deeper into this over the coming weekend and see what I can find.thx again

[kfxmatt]

Since I’m not sure about any part of this a/c system,I’m thinking I need to start at square one.i tried the valve on the line near the compressor and nothing came out at all.im guessing it’s empty.i ordered a complete seal kit from napa.do I need a vacuum pump to clean out these lines after I change the seals?and where can I get the tool that seoerates the a/c lines?

[KevinK]

Ok, take a step back. With the engine off, try turning the ac compressor by twisting the clutch assembly. This will tell you if the compressor is seized.