OK,

The compressor is cycling on for 2 seconds, then off for 4 seconds, repeatedly. The pressure on the low line will build to 45 psi, at which time the compressor turns on. The pressure quickly drops to 20 psi, at which time the compressor cycles off.

I have a recharge hose and a new can of r134a. I hooked those up, jumpered out the low pressure limit switch (blue wire to gray wire, BTW), after which the compressor ran continuously. I ran the compressor for about a minute, then hooked the limit swith back into the system, after which the compressor began to cycle exacly as it did before.

I left the r134a hooked up and let the compressor cycle for about 5 minutes to see if the cycle period became longer in duration - no change. I verified that gas was available at the end of the hose (cracked the valves and listened for gas).

I did notice that the recharge hose was pulsing with the compressor, as if back pressure were building in it and then relaxing. Also, the can of refrigerant is not getting cold - shouldn't it get cold as the fluid changes state to a gas?

My next stop is a pro to evacuate and recharge the system. How much r134a should go back into the system - does 1.65 lbs sound right?

Also, are there any other tests that I can make on system components to keep down the cost of repair? I did not see a sight glass on the receiver/drier to inspect the flow of the fluid for air bubbles - is there one? Where is the high pressure switch located?

Thanks for all of the help - my wife and kids thank you, too.
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Ten Sleep 1980 245DL 1995 850 Turbo 1997 Dodge Dakota 5.2L

I pulled the connector off of the low pressure switch on my AC system - just two leads, blue and gray. An essay I read stated that the colors should be green and gray. What do you guys think?
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Ten Sleep 1980 245DL 1995 850 Turbo 1997 Dodge Dakota 5.2L

By know, you have figured out that there is no high pressure nozzle, and the low pressure switch is just forward of the wirewall.
Do not use any stuff that is a sealant for leaks. It will not work, and the guys that fix HVAC systems will walk away if they find it in your system. Just add one can of r134a to bring the pressure up.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)

Hate to say it but I'd be willing to bet it's the evaporator that's leaked your gas out. Read Meb's post just above (or maybe now, below yours here) on the evaporator change. You can fill with dye and use a black light to check to begin with, as you stated- which may be a good first step. Most likely leaking area is the evap. A suggestion: Use a guage and see (from the low port) if there is any pressure at all in your system. If it's the evap., most likely ALL of the gas has leaked out. If it's just shrunken 0-rings over the winter, you'll have some pressure left, but probably not enough to turn your compressor on. You can use a jumper wire to force the compressor to start if it won't on normal A/C operation. You'll need it turning anyway for it to fill properly with gas. In regards to the jump points, you might want to check out www.matthewsvolvosite.com in the database section. Good luck and let us know how things go.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.

the fill is right in front of the power steering pump and down, yes it does have a low pressure cut off switch, you will probably find one of two things, either your eveaporator is leaking (inside the car behind the dash) or the ac line that runs in front of the subframe under the car has gotten porous