hey guys, just wondering if anybody out there has any information that could help me fix my AC in my 97 crown vic. It's been blowing hot air all summer and I can't figure out the reason why yet. It's charged with freon, and the ac turns on, but it blows out hot air. I do, however, hear the ac clutch turn on and off every few seconds. Would this be a bad low pressure switch? i've read on other forms about bypassing the switch too see if that helps.., i've tried this and it made my ac clutch engage constantly, but i couldn't tell that the air was getting any colder after i waited a few minutes. I'm pretty sure there's no leaks because the freon level stayed constant and showed it was charged for about a year even though the AC didn't blow out cold air. Does this sound like a bad low pressure switch?? any help on here would be greatly appreciated since i don't have any $$ to take it in to the shop. thanks guys!

 

Could you please help me with a few answers?
How were you able to tell the freon level stayed constant?
If the system is low on refrigerant even with the clutch engaged constantly it can't cool sufficiently. The low pressure switch generally will open around 28 psi and close again around 35 psi. Those are ball park figures. It does sound like the system is low on refrigerant. Something else to consider is the blend door which if it isn't operating correctly will allow the cooled air to mix with heated air from the heater core causing poor or very little cool air to come into the vehicle. Also an overcharge of refrigerant will give poor cooling, but the cycling (lo press) switch will never get pressure low enough to deactivate the magnetic clutch. Did you check to make sure there is sufficient air flow through the condenser which is in front of the radiator?

 

well, i could be wrong. i assumed they stayed constant because it didn't work last year either and we tried to re-charge it and it said the level was fine. When we went to add freon in it this summer, the gauge still showed the level was fine, so thats why i assumed the freon level stayed constant and charged. I also checked the condenser which seems to be allowing good airflow.. thanks for your help so far, if you got any other ideas or thoughts i would really like to hear them!

 

I am now assuming you have the manifold gauges available to see just what is happening. With the gauges connected, the control panel set on max, blower on hi and the RPM up around al least 900- 1000 RPM you should see the low pressure gauge come down to 28-30 psi. If you are not seeing this , let us know just what you are getting. If it is coming down to that reading and going up rapidly , it's just low on charge. Will watch for your answers.