JW3

I dont drive the truck as much as I once did,but would like for the a/c to blow cold. The cluth on the compressor is kicking on and off about once every 45 sec. The small line coming out of the firewall is quite cold, but the larger one is warm. Question is does freon need topped off from time to time, or do I have a leak. the fan is blowing just hot. Thanks for any help.

Busboy

If the truck sits for long and doesn't get driven then the front seal on the compressor dries out and this causes the freon to leak out. It's evident by the front of the compressor being oily. To stop this just run the AC once a month for a few minutes to keep it lubed up. Yours just needs a little freon.

JW3

thanks busboy. How big a deal is cahrging the a/c.. I am a capable wrench, but I have never jacked with a/c freon.

EverydayDiesel

adding r134 is not that big of a deal if you understand the basics but your wasting your time if you dont find the leak first.

you need a set of manifold gauges then find the correct pressures that your system should be at

remember ALWAYS add to the cool/low side
NEVER add to the high side

Busboy

Like Everyday says your wasting your time if you don't find the leak first. If the front of the compressor is oily it was leaking. I would clean it off and recharge it as the seal will probably re-seat itself. The Evaporators on these trucks are known to rot out the bottom, (I replaced mine last year) but as there is still some freon left in the system I suspect the front seal.

justme-

Don;t assume you will always find a leak- all ac systems will eventually leak down no matter what maintenance has been done if a regular recharging is not done. Yes- look for the leak, but if you don't find one, don't freak out- it's not always going to show up, or be fast enough to matter.

Recharge the system with a dye can (look in the auto AC section at a box store or the auto parts store) then (after cleaning the engine and ac connections) run the ac and look for dye with a UV light. If there's a fast leak you;ll see it (the schrader valves in the charging ports are often the cause of most non compressor leaks). If you don;t find a leak, look for improvement in the compressor run time (longer cycles) and colder air- charge as necessary for proper operation or bring it to a shop to have charged where they can put gages on it to see how much it needs. I have had a bad valve in mine for years- but I don;t care much for ac anyway.

JW3

thanks for the help men

justme-

one more thing- in the auto ac section you'll find a gage and adaptor kit thing that lets you check pressure on the low side and add 134- use that- unless you do AC systems a lot there is no need for the manifold set (too $$$) It is incorrect to say only add to the low side- you add to either side depending on what is accessible IF (and ONLY IF) you know what you're doing with AC systems. If you add liquid on the wrong side you'll pop the compressor.

EverydayDiesel

Adding r134 to the high side can cause the can to blow up in your hand. In other words DONT DO IT. It even says not to right on the side of the refrigerant can.

Busboy

While I have seen people do it but only with 30lb jugs and proper gauges and only with the motor NOT running after the system has been evacuated, I never do it and would never advise anyone to especially with small recharge kit cans. That is why they changed the size of the HP fitting in the late 1970's because of a can blowing up in someones hand and a law suite followed.

1-2-3

You can get a decent set of gauges at harbor Freight tools. Good enough for home use. I don't ever advise anyone to just add freon. You have to know what is not making it cool. Although a leak is most likely, there are other issues that can happen and if you just dump freon in without knowing, you can seriously overcharge a system and do some major damage to it and possibly yourself.

The simple gauge at the auto parts store that comes on the filler kits are highly inaccurate. I used one to charge my system, but I also have a set of real gauges to check it with The cheapo gauge would show diffrent every time I hooked it up.

justme-

Harbor freight manifold is junk- don't waste your $$.

I said you can add 134 to high sides IF you know what you're doing.... that includes knowing WHEN to add and when NOT to add. I've had some experience on Ac systems since I was a kid- been adding R12 with a manifold set since about age 10. Am I an expert- No, but I know what to do and what not to do.

If you know nothing about ac systems at all- have someone look at it who does, the compressor cycling that often means it's low on gas, and the gage on the store bought cans is accurate enough to bring the system back to working.