Air con problem

Today was about 70 degrees i took my xj 99 4l for about an hour drive with the aircon all running fine,then as i was slowing down to pull into the store i noticed it started to blow warm air through i did smell some kind of burning smell now the aircon will only run for about 10 mins then blows warm it seems i have to turn off the engine let her cool down for about half hour then the aircon will run again then same thing cuts out and blows warm after about 10 mins im wondering if she needs more refidgerant any help would be appreciated thanks A.J

Low refrigerant would cause the system to blow warmer than normal at all times.

Check the auxiliary fan is coming on when you turn on the AC. If you were moving fast enough to force air thru the condenser, without the fan, the AC would probably work normally, but as soon as you slowed down, the AC would likely shut off due to the pressure climb in the system (from the non-working fan) and the system would blow warm air.

A bad fan will cause the system pressure to build up, and the AC compressor will cut out from the high pressure switch. It would take more than a few minutes for the pressure to dissipate, so even if you got moving fast again, the AC wouldn't come back on for 1/2 hour or so.

thanks rick i will look into that tommorow

Do a search on "low pressure switch". It's a common problem that causes your condensor to ice up, thereby blocking the flow of air. Once it melts off, it runs fine until it ice's up again, and the cycle repeats.

Simple replacement of the low pressure switch fixes the icing up problem...

i have to disagree here low pressure switches rarely go bad if its icing theres a reason dirty evap coil etc, anyways without more history its hard to diagnose i agree with checking the aux fan, mine had probs(98 xj) bought one on ebay for 30 bucks took care of my overheating probs ac worked fine afterwards