fastman454

Ok, so my well taken care of xj's a/c just didn't work at all today. I have 123k on odometer. It worked since I've had it but I do think it might have not been as cold a week ago as it was when I bought it....but its been extremely hot out so it might have been working fine just not nociably cold. So I started from the basics....compressor wasn't kicking on so I checked pressure with a guage and it was reading low, about 5 to 10 psi. So I bought some basic oil and a can of 134a and with a/c on full blast I added oil then refrigerant. Went up to 50psi which according to guage was top of safe and full. Compressor kicked on and off while filling so I got it working again (I think) ......but still no cool or cold air. It's actually rather warm air but not extremely hot like it was when I moved it to hot on guage. It feels warm like it normally was if I had guage in the middle on the controls before all this problem. Any advice? Is it something with my a/c system or my controls?

Sloassmac

Well, I don't know the problem with the ac system. But, (correct me if i'm wrong guys) when you turn the thermostat to hot, all it does is adjust the damper inside the climate control box from the evaporator to the heater core. The engine is always making heat, and its always flowing through the heater core. Which is the opposite for the A/C which only operates if you have it on. If you turn it to "blue" without the A/C on, all it does is blow outside air IN, but if you turn it to "red" while the A/C is on it still blows air across a hot heater core. Im just saying, I think your experiment might be flawed. If its just warm on the blue, then the A/C is probably not doing anything and your just feeling the ambient air from the engine compartment.

Gorillaxj

For this year of XJ that is mostly correct.

It sound slike the A/C was low/empty of frean, when you started working on it. most AC systems should be (roughly depending on ambient temps) close to 30psi on the low side, and 150 on the high side with some changes when the comressor is cycling. It is also important to have the AC system evacuated properly and hae a vacume put on the system to remove any possible moisture or contaminants before recharging an AC system.

when I am diagnosing an AC system I go in this order.
check for compressor activation with a/c on.
check freon levels. (if low look for leaks)
check fan operation across condencer with AC on.
blend door operation/control outputs

I have never seen this but have read about the vacume ball behind th bumper and how if broken/leaking it can cause the Climate controls to not fully operate... Don't know the truth/extent of this but its an idea of somthing to look at lol. good luck.

fastman454

Soooooo.....I need to go and have system evaccuated and then fill it up again?

lynskynbnd

When the AC is running with inside fan on high, feel the thicker(low pressure/suction) line at the compressor. In a fully charged system it should be COLD. This applies to all vehicles.

(assuming that the condencer fan is running, the fan cluch is engaged, the expantion block works, there's enough oil in the system, the condencer is not restricted internally, there's no moisture in the system, the system is not overcharged, the compressor has good valves and is compressing.)

Yes, it's a good idea to have an empty system evacuated before charging to get all moisture out.