A/C Hot and Cold

My wife's 1999 Windstar has a problem with the air conditioning. It will run very cold sometimes, then run warm others. I tried to add more refrigerant, but the gauge on the can indicated the pressure was okay, and I should have it checked for mechanical problems. I can hear clutch engage when I turn on the air, so I don't think that is the problem. Any ideas before I spend the $$ and take it to the shop?

thanks

This subject has been covered, so I would suggest a search on this forum.

... but "simply put", in hot weather if you open the doors so the system can never "catch up" ... the ac clutch should never disengage. It should keep struggling to cool off the open cabin.

(If however, your system has been "serviced" before .... well then, all bets are off. You may have air and moisture in the system and "total evacuation" is necessary.)

If your system has never been worked on ... or has leaked to the point that moisture and air can leak into the system, you have a chance. There are some electrics that sometimes are fouled up .... but usually it's refrigerant pure and simple. Well, maybe not "simple".

When people read the gauge they often don't realize it's the LOWEST reading that you are looking for ..... the one that occurs just before the clutch disengages again. This "lowest reading" should be above 25 psi or whatever the side of the can indicates ...or keep adding refrigerant til its up where it should be. Always be patience and don't rush the procedure. If you mamage to get liquid (instead of gas) refrigerant into the pump inlet, you will hear it destroy itself ... not a pretty sound!