I have a 1996 XJS.

I've had some intermittent cooling issues with my AC. I decided to check refrigerant levels. Here's what I found:

It's 25C outside. AC is running maxed out.

When the Low Side Hits 75PSI the compressor turns on then drops to 35PSI

On the High Side I'm fluctuating between 175PSI and 125PSI

The compressor runs for about 7 seconds before it stops and then about 13 seconds later it runs again.

 

I think you may be under charged. Would expect longer compressor runs and 200 psi outlet pressure.

 

See this thread, I like the approach for determining the right amound of charge.

I'd expect to see more than 100 psi on most cars as well

 

Can you repost the link or tell me what the title (and OP) of the thread is? I'd love to look it up.

It seems the high side readings are well within range according to the service manual. I'm not sure how to read the low side since the graph shows a relationship between the low side PSI and the evaporator temperature. The low end, at 40PSI equates to 41F air whereas the high end of my readings show 70F air when the gauge gets to 70PSI.

I can't be reading this right, can I?

 

I think the reference is to this thread: https://www.jaguarforums.com/forum/x...estion-148657/

I agree, I think you are undercharged. The low side seems about right at 35 psi, but the high side should probably be a bit higher. A short cycling compressor is a sign of being undercharged.

 

Thank you for that link, it is indeed helpful.

I think at this point, I will check the temperature of the air coming into the cabin, and possibly add more refrigerant. I will be mindful to not exceed the high side pressure limit while doing so.

Thanks again.

 

Yup, thats the thread, specifically post #9 by Jagboi64. Sorry i messed up the link earlier, was on my mobile device