92 Grand Caravan AC Problem

[Rschrei518]

Ac hasn't really been working to good compressor engages AC fan goes on and small ac hose gets hot big one gets a little cool i am only getting a 5 degree delta t today i was looking under hood and felt the hose which goes into the heater core and it felt hot!! Is it suppose to be hot when ac is on? Then i notice that the vacuum hose which goes into the heater control valve was just hanging by a thread and i touched it and it broke off and now it is too short to even reach the heater control valve. Does this sound like my problem if so i am probably going to change the heater control but how do i go about fixing this vacuum hose it goes into the firewall? When there is no vacuum is the flow to the heater core on or off? Any help here would be greatly appreciated

[jpb53]

Fix the vacuum leaks first. Probably doesn't need a control head. In most Chrysler systems no vacuum is the same as off. Go to a parts house and buy some hose that fits tight over the plastic hose to repair the lines, then see how it works.

[webbch]

Yes, unless I'm mistaken (it's happened before ;-) ), the heater core should always be hot, because engine coolant is running through it (there may be a valve that controls flow, not sure). Behind the dash, in the HVAC stuff, there is typically a mode door controlled by vacuum that directs the air from the blower motor over the heater core when the mode door is in the "heat" position. If a vacuum line is broke and the "default" position of the mode door allows air to pass across the heater core, then the air would tend to first pass across the evaporator, cooling it down because the A/C is running, then due to the vacuum leak, it would also pass across the heater core and get warmed back up again, so your net effect would be blowing warm air on you.

Alternatively, you could just be low on refrigerant, but you need to know low and high side pressures at a minimum before adding refrigerant, and the correct way is to pull out the current charge and weigh it (to verify an undercharged condition), then meter in the exact amount necessary. You CAN charge by pressures (low AND high side) and measuring vent temps incrementally, but you really have to know what you're doing, and it assumes the rest of the system is operating correctly already (if using incremental vent temperature readings)