Ok this is my girlfriends account and she posted up here about two weeks ago, i have taken a look at the truck and gone through a few things. i still need help with this truck. here is the skinny
1. ac doesnt work.
2. the compressor runs the whole time and doesnt stop.
3. i can cycle it by pulling the relay but still nothing gets cold, no frost or condensation on the pipes near the condensor, nots blowing cold.
4. the pressure is in the green on my good gauge, not a stupid can gauge.
5. i'm outta ideas any help is welcome. i do know my head from my *** so anything that might steer me in the right direction would be awesome.

 

sounds like the blend door is stuck in the hot mode

 

and how do i fix that..where is it located

 

Check your vacuum lines on the firewall. Like said above, if your blend door is locked open from the heater core you would be hot in the vent. If it was working before and just started this, its a good possibility is something simple as in the hvac controls. The blend door mixes the cold and hot air from either the outside or A/C system. Its under the dash.

My old 96 with 300K + still has the original A/C system in it.

 

ok.. yeah the truck was in an accident years ago. got fixed and they replaced everything on the from end. the AC worked after that and then quit. so i can go check the vac lines, and take a look under the dash. so with the door stuck in hot mode would this keep the compressor from cycling

 

If the vacuum is the problem, and you can't get any in the hoses, the vacuum pump, located in the back side of the power steering pump can be rebuilt or replaced. Sometime the lines will have a "Y" in them on the drivers side firewall. If you been in there doing anything its easy to knock one off.

If the A/C is working properly it may run continously untill it reaches a point were it will cycle. Don't think because the heat is on 100% that it would keep the A/C compressor running.

If you don't fine anything send "Spooler" a PM. He's good with A/C Stuff. He's not on line right now or he would have responded already.

 

With the ac running, a quick check is to see of the lines under the hood are sweating. if so, then there's a fairly reasonably good charge on it. if not, you may be low on freon. If the lines sweat, and the air is blowing out of the right place, yet way hot, then the blend door is stuck.

 

no sweat on the lines.. but the pressure is where it should be..

 

the air coming out of the vent isnt hot. it is like the truck is just blowing air. the truck has heat, then when i switch it to ac. it blows outside temp air.

 

What is the actual pressure of the low side, with the system running. Not just in the green

 

Touch the low pressure lines near the drier if they are cold then the AC is working and you have a temp control problem. The blend door is operated by either an electric actuator or a hardened steel boden cable. (I'm not sure which one the 1996 has) The cable kind adjustment can slip and not give full travel of the door or the anchor point breaks while the electric kind can break the drive point. Both simple fixes. Look under the dash next to the hump on the passenger side if electric there will be an actuator there. If no actuator then it's cable driven. It may just be out of adjustment or the cable has broken off at the anchor point. You can just use a plastic tiewrap to secure it in position if you can't find a replacement one. If electric there is a replacement part that is better, if you do a search on here you will find it.

 

Yea. I'm finally leaning towards door issues.

 

Just had a similar issue with mine. The lines near the accumulator got ice cold but no AC while jumping the Low pressure switch. Gauges read goofy too. Low side would pull a vacuum and hi wouldn't go over 150.
It turned out the accumulator was bad. Very rare but it happens and happened to me.

 

What is more common than a bad accumulator/receiver/drier is a plugged or partially plugged fixed orifice, both these will create a vacuum on the suction side if the compressor continues to run. He did say that the suction pressure was in the green though (count 1 psi for every deg F of core temp). To properly T/S a gauge set that gives the Hi and low sides is required.

 

ok well lets say this again. i have no cold/ sweating/ or anything related to cool on the low pressure side. the compressor is running full time. doesnt cycle. i'm pretty sure its not the door at this point. because the low pressure lines are not cold. just trying to get that point across..