First off I'm glad there is a forum for Durango owners and have read up on several posts and could not find a problem like mine.
My 2000 Durango 5.2 SLT is not blowing any cool air at all it went from cold to hot while I was driving it to work, it started off with the A/C blowing cold air while I was driving and then it started to get warmer as I was driving to completely hot and has been hot ever since and thats been several days now.

The compressor engages when I turn on the A/C selector switch to the on postion and disengages when the A/C selector switch is in the off postion. This has me scratching my head, I know from the past if the compressor is not engaging there is a low refrigerant pressure in the system, it was in need of a recharge of refrigerant.

I know I need to check the pressure in the system, but what would cause it to blow hot air even though the compressor is still engaging like that ?

any helpful tips would be great

PS found a TSB # 24-03-96 A/C does not cool A/C clutch engaged Check PCM with DRB III, I cant get a viewable page on this particular TSB #

again any help would be great

 

First, you can try to see how the refrigerant lines feel when the compressor is engaged. The smaller line should be the hot high pressure line and the bigger line should be the low pressure cold line. If you can feel a that both lines are hot and cold, the compressor is working fine and there is enough refrigerant. If the compressor kicks on and off and you do get temporary cooling. chances are, you may have moisture buildup within the refrigerant and you will have to take it to a shop where they can re-cycle and/or filter the freon to get rid of the moisture.

When moisture builds up within the refrigerant, it will clog up the pressure regulator that actually converts the high pressure freon to a low pressure freon. As freon and temperature are proportional, a drop in freon pressure results a drop in temperature. Moisture starts to freeze on the cold side of the regulator causing a stoppage of freon flow. This will also cause a gradually drop in freon pressure on the low side. It will eventually trigger the low pressure safety switch to shut off the compressor when freon pressure drops too low. After the compressor shuts off, both sides of the low and high pressure lines will slowly equalize. With pressure rising on the low side, temperature will go up above freezing, melting away the moisture. Once pressure is nearly equalized or when the pressure slowly goes up on low side, the low pressure safety switch will re-enable power to the compressor. Then this cycle will start all over again. When moisture starts to freeze up, that is when you start to feel the air gradually warming up as there is not enough freon to keep the coil cold as warm air passes thru it. This moisture problem also causes your compressor to cycle on and off and can look like symptoms of low freon charge.

 

I have checked both lines are they are hot but the compressor remains engaged at all times like if it were ok, I can turn on the ac and the compressor cltch kicks in and remains engaged with out kickin off and on. This is what has me puzzled. it constantly blows hot air not matter when I try to turn it on

 

Based on your statement, it may seem the compressor may have gone bad. You said that both lines are hot. One (smaller) line should be hot, and one (bigger) line should be cool or cold. Only way to confirm is take it to a reputable A/C shop to perform a diagnostic check to make sure the valves on the compressor is working.