Dear friends, My 1993 S-Type R seems to take awhile for the AC to come on when commanded. ie When I turn on max cool on hot day it just takes a while for the AC to start blowing cold - awhile as in 15 minutes to half hour. It seems kind of random . .. I checked the low side R13A pressure and brought that up to spec. Any ideas would be appreciated from this vast brain trust. Regards Biggy

 

Biggy - sounds like your freon could have a low charge - you fixed that up I presume. Next step would be to check the hi/low pressures - compare to specs at ambient temp. (Another words - pressures will be slightly higher as the ambient temperature increases)

If your pressures are in check - monitor as you may have a slow freon leak somewhere.

Also, could be your DCCV beginning to malfunction as well, but my $ is on a low freon charge/slight freon leak...

 

Do not check only one side of the A/C and add anything. Get a proper set of gauges and see what the high side and low side are doing. Do NOT top it up!

The system is all interconnected and the low side might be reading what it does because of what the high side is reading. But you don't know what the high side is doing.

Now you have no idea how much refrigerant is in the system. Remember over charging will cause problems just like undercharging will.

You could have something simple like a worn A/C clutch that has nothing to do with the refrigerant.

Has the DCCV been changed? Is the temperature even across the vents when both temperature controls are set to the same temperature? How does the heat work?
.
.
.

 

I need to check the voltage to the clutch and the clutch operation - the heat works fine - I will try splitting the heat and cool from side to side to check the DCCV .. as I said - when you call for AC - it will eventually come on .. but not immediate - I thought maybe the OAT sensor was flakey - turns out that didnt fix the problem.

 

I can control extreme hot and cold from separate dash vents ..the issue seems to be delayed engagement of AC ..even on extremely hot days .

 

When you have it set for A/C get out and look under the hood to see if the compressor is turning.

Does the blower seem to move enough air? All speeds OK?

It might be the that the A/C is OK but the DCCV is letting the heat come on too. You can clamp off the three hoses going to the heater. This will eliminate the DCCV. They are on the passenger side attached to the inner fender. Pretty easy to see.

Don't forget you added gas. You need a set of gauges and read hi and low side plus measure temperature at the vents inside the car. If you don't do that first you are wasting time and money. Those numbers tell the health of the A/C system.

Does the outside temperature read correctly?
.
.
.

 

I had something similar happen where my AC would take 10-15 minutes for the clutch to engage. Once the clutch engages it would cool normally. It was the relay; you can switch them to test.

This thread got me thinking and sure enough, it was a weak relay!

https://www.jaguarforums.com/forum/s...d-again-77054/