92DIESEL

My compressor cycles on and stays on when I put the A/C on BUT, I get no cold air. The line to the condenser gets warm and thats all.

I don't have gauges and the system is original/ intact (R-12)

I get no condensation anywhere on the lines, and they do not get cold.

Is there an inexpensive way to check to see whats wrong, or do I need to bring it to a shop to get it checked out.

Any suggestions, BC47, Jim Lane... anyone know these systems well enough to help... I know your out there.

Thanks in advance,
Michael

QIK2D

almost sounds as if the compressor is bad. it kicks on but doesn't make any pressure. a quick hookup with some guages will show what's happening. i'd bet your high and low side readings will be close to the same.

i dont think it a low charge, the compressor would short cycle or not kick on at all. those who now more about a/c will chime in
daryl

dpuckett

If the charge is low, there may not be enough stuff in the system to compress. I'd hook up some gauges and see what's giong on. I am in a similar boat- my AC needs service. I think I am going to buy/ borrow some gauges and do it myself. My hose came off the back of the compressor, so I know there is no original R-12 in there. I also know i need to replace the dryer and h-valve.

Daniel

DieselSmith

last summer I had mine converted to R134a... Lord knows I couldn't have done it myself. Best decision I've ever made lol. I can start it up and let it run for a bit while I'm working, hop in and cool off. It could be a little colder but thats the sacrifice you make going from R12 to R134, less cooling ability but WAY cheaper. This is in 95 degree heat and about 70% humidity. I'd have to say it works. that was pretty irrelevant but I thought I'd share!

vinny

I just posted to a thread about propane instead of freon so it should be right at the top...a very interesting read for sure.

If you do need a compressor, in that same thread Bill Tomlinson said that the older Mopar compressors will fit when you grind-off one of the ears.
Personally I'm going to give that a try because, it's hot, my AC doesn't work, and I have a fresh Mopar rebuilt compressor here...I'll let ya' know how that works for me.

I just need to get a look at one of these homemade propane to AC system adaptors so I can make one and start using propane instead of freon and r12a.

Vinny

pred

If the compressor turn on then right back off and makes no cold air, It is most likely low on refridgerant, There is a low pressure switch that sounds like it makes when the compressor is off, then when you kick the ac on, The compressor makes, therefore pulling the refr. from the low side, and putting in the high side, therefore cutting off the compressor because the low side went too low for the switch to make, You need a charge, I doubt that the compressor is bad.
R12 is still available in 30lb cylinders, But the cylinder is about $3,000.00,,,,,, Time to switch over to something else.

wannadiesel

Compressor comes on and stays on, line to condenser gets hot. I don't think it's low because it doesn't cycle.

92DIESEL

Thanks for the replies, I will ask around and see if I can scare us a set of gauges to see what the pressures are.

Please kepp any and all ideas coming.

Michael

Jim Lane

Michael,
Check your sight glass when the AC is running and let us know what you see (it is on top of your reciever/dryer) you will probably be seeing oil streaking through.
So the suction line is not even cool?
Jim

MoparMarv

R12 gauges are just about give away prices these days. handy thing to have. 134 gauges are a little more pricey. Since the compressor is cycling and no cold is blowing I'm going to guess the system has blockage or the charge is low. Gauges should be able to nail it down for you.

wannadiesel

Suction line is room temp, as are all the other lines except the line from the compressor to the condenser.

(I was there but did not have gauges)

QIK2D

if the compressor kicks on and stays on it is not a low charge.low charge will either not allow the compressor to kick on, or will short cycle the compressor as it draws the low side too low, but it will not stay on.

a bad compressor (as i suggested earlier) can kick on and stay on, but have an internal bypass that will not allow it to make the high side pressure. guages show the same readings high and low, just a little to the positive.

the discharge line is hot and the condensor to drier line stays room temp. sound like a restriction in the condensor. have you added oil lately. too much oil will puddle in the condensor and restrict the flow. basically your compressor is squeezing the same freon over and over again (cavitating). get some guages on it. if the condensor is restricted, the low and high side will be close to the same and could both show a vacuum.

92DIESEL

I haven't gotten gauges yet, But to answer Daryl's question...

No I have not added anything to the system. It is completely stock from the time it left the factory. This truck was built for the New Jersey Turnpike Autority (thats why I don't have any interior, no headliner, plasic trim... you get the picture) and they kept service records for everything, (the only time the truck was shut down was for routine maintance 10yrs worth)

The A/C was ice cold until my Dad parked it for about 6month before I got it. from that time on the compressor kicks on and stays on but no cold air.

Sorry for the long post, but I just wanted to give some history

Thanks again for the replies,
Michael

Ron E

If the little orifice in the expansion block is blocked, will the compressor cavitate?

QIK2D

yes, but it will show the high side pressure to go through the roof and a vacuum on the low side. also if it was that far along in the system the line coming out of the condensor would be warm. the room temp liquid line from the condensor to drier suggest a blocked condensor. it should be warmer than room temp but cooler than the discharge line from the compressor. guages will solve this mystery very quickly.

daryl