Another A/C ?

[sseaman]

My 91 is only blowing hot air, last summer it worked fine, this year nothing. Everything sounds like it is working, and the sight glass looks as it should according to the fsm. Could there be a door/ diverter somewhere in the dash thats not functioning properly?

Im ready to rip into it, I just dont want to start throwing good money at a car worth $2-3k

[inkpot]

Howdy! If you are low on freon, the system has a safety switch that will prevent the compressor from running. This is because the freon is also the lubricant for the system, and without it, it will burn out the compressor. When you turn on the AC, does the electric clutch on the compressor engage the pulley to drive the compressor? If it is not pumping, then you will not see any bubbles in the sight glass. John

[sseaman]

yes i see bubbles, as stated everything looks to be functioning, just no cool or cold air at the vents

[jonheld]

Top center of the firewall is the heater valve. Make sure this is being thrown correctly by the cable attached to the heat/cool slider in the dash. It sounds like your heater valve is always allowing coolant to the heater core.

Also with regards to the sight glass, you should only see bubbles when the compressor first kicks on and right after it kicks off. After running for a few seconds it should be clear. If you have constant bubbles in the sight glass, you are low on gas.

[e9999]

can you feel a difference in temps between the suction and discharge sides of the compressor?

(there is an extensive troubleshooting section in the FSM you could follow, some steps would require gauges)

[TX Cruiser]

Originally Posted by inkpot

This is because the freon is also the lubricant for the system, and without it, it will burn out the compressor. John

Who ever told you this is dead wrong. Some freon charges have oil in it, but with out oil nothing is going to work. The system needs as little as 5.5 and up to as much as 7.5 ounces of oil.

Grab a hold of the fat ac line on the metal portion, if it's cold, you have a heater valve problem, if it's not you have a leak in the a/c system.

How is the fan clutch on your rig? Its getting hot, and the high side pressures can spike at a traffic light if the fan clutch is bad, and your a/c won't be able to cool worth a damn.

If you see any portion of the a/c system that has a grimey, black, oily, nasty filthy, crud on it, you have found your leak, if the compressor is coated from the pulley back, you blew the front seal.

If you want, I can help you out.

[sseaman]

it used to blow nice cold air at highway speeds, and warm a little when in traffic. Its not blowing cold or cool at all. John, i have followed the fsm steps, thats why it seems odd for everything to run and no cold air.

Back under the hood

[sseaman]

Originally Posted by jonheld

Top center of the firewall is the heater valve. Make sure this is being thrown correctly by the cable attached to the heat/cool slider in the dash. It sounds like your heater valve is always allowing coolant to the heater core.

Is there a way to tell if the valve is closed or open?

[NLXTACY]

Other than looking to see if the slide moves? If someone is inside the cab and moves the temp selector you can see it move (truck must be turned on!)

Other than that I would say you would be taking it off to make sure the actual divertor is still operating. But I've never actually played with the LC's so I'm not 100%

[jonheld]

Originally Posted by NLXTACY

If someone is inside the cab and moves the temp selector you can see it move (truck must be turned on!)

Truck doesn't have to be on. Cables move without battery power when you push the dash slider.