Earlier this year I replaced the AC Pressure sensor located above the
condenser, there was no Schrader valve located under the sensor,
so I took it to an AC shop which vacuumed the system and refilled with
the correct amount of Freon.


Since then the AC has been working great until last week;
my air conditioning blows warm air after I start driving,
I have to turn the AC on and off once or twice before it starts
blowing cold again. After it blows cold it gets very very cold though.


Any suggestions what could be the problem?

I do have a working JLR SDS but limited knowledge how to use it.




Thanks

 

How long does the AC have to be off before it blows cold air again?
If its like 5 or 10 minutes it could be an icing issue which translates to a system leak.

 

Icing (ice blocking the evaporator) and system (Freon) leakage are not related.

The OP said the system was evacuated. If done properly that would remove the moisture. Since it operated normally for awhile, this seems to be the case. The system is pressurized and will not pick up moisture from the outside lower pressure environment. So the expansion valve should not be freezing.

You need to first determine if the compressor is turned on when the hot air is blowing.

 

Maybe the system needs to be evacuated again, the drier replaced, then the system recharged. Looks like some residual moisture is icing up.

 

Maybe it's as simple as a loose wire on the compressor clutch? Does the compressor turn when you're blowing heat, or just the compressor pulley? Maybe the clutch has a short..... I'd try obvious and cheap fixes before paying another $100+ for a recharge that may not fix anything.

 

The compressor on the X150 doesn't have a clutch. It is "a permanently engaged variable displacement unit"

 

Even in the "ECON" mode? That's just stupid.

 

A little FYI

 

Well then.... forget I said anything.


These dang punk kids and their new technical doo-dads...

 

This could be the issue.
TECHNICAL BULLETIN
JTB00380NAS1
19 DEC 2014

 

Thanks for the replies,




So after sitting overnight, I start the car and the AC will not blow cold 50% of the time unless I turn the AC off and then on again, sometimes 1-3 times.
After that it will start to blow cold within 1 minute and runs very cool and efficiently.


if I don't turn it off and on, it will continue to blow warm air.

 

Once you get the AC to start working, how long does the AC continue to function? Will it eventually stop on its own - or will it continue to run as long as you are driving the car?

 

it will continue to work fine

 

It is sounding more like the auto climate control system has a problem. The 1st thing I would check is the freon charge in the system. If it is full then the CC system is not functioning correctly.

 

Have you tested to set temperature to max low before you start the car? Could be a temp sensor that is on it's way out or has a bad connection.