My 2008 5.7L 1500 is getting long in the tooth. But I plan to keep her going! Today the ac only blows hot air which really "blows" in this heat. The truck has been sitting up for a few weeks and not started. Battery needed to be jumped. Not sure if that matters. AC is one of the few things I have never really worked on. So I started looking around and see that the compressor comes on sometimes but is mostly not engaging. I can get the clutch to engage by disconnecting the pressure switch and reconning while the engine is running. But it still just blows hot air even with the compressor on. Then I noticed a stain on the coolant hose that touches the bottom of an ac line (see pic). That hose is new last year from a water pump change. It should be clean like the rest of it. So I am wondering if the hose is leaking or perhaps there is an o-ring blown out where this hose bolts to the condenser at the front of the truck??? Has anyone seen this before?? I have a set of ac gauges on the way. But have never used them.

 

Check both hoses, and see if one of 'em has rubbed thru. The A/C hoses are pretty stout though..... I would think the radiator hose would fail first.

If the compressor cycles, just not very much, then you are low on charge. Being 15 years old, that doesn't come as a surprise.

 

I did check where it was rubbing. If it is leaking, it can't be seen or felt. I am wondering if it blew out all of the frig, and is completely empty. It kind of looks like the oil in the frig leaked out for a while and ran down to the radiator hose. If it did, it is not doing that anymore, or is a very slow leak. I am leaning toward the hose connection at the condenser. I am hoping there is a blown out o-ring there. But I am not sure if one even exists.

 

Never worked on it? It could be the Schrader valves. They are the most commonly overlooked parts that tend to leak.

I'll be doing the same thing soon when I replace my heater core. I'll have to discharge the AC as well. So I've been stacking extra work to make sure I don't have to do it twice. I'm replacing all the AC doors and those 2 valves just to be sure. I already know the valve on the low side has a leak.

 

I never have, and can't remember if any shop has. Pretty sure no one ever has. My wife's jeep had a bad valve and the mechanic who did ir said the whole hose had to be replaced. Can you replace just the valves on the ram? I also need to replace my vent doors. I have been avoiding that for a year. Which replacement doors did you choose?

 

Schrader valves are the valves that are in the AC high side and low side ports. If you unscrew them the refrigerant will all discharge from the system. There are tools that let you replace them without losing refrigerant but space may be an issue. For instance the low side valve is right up against my firewall so I can't get the tool in there to replace mine like that. So I will have to have my system discharged before I can replace it.

 

UPDATE: received my gauge set today, and get readings I did not expect. Its about 90F here today. With engine off, I get 20/25psi L/H. With the engine on and compressor running (jumped), I get -10/75 psi. I am guessing this means that all or most of the refrig has leaked out. But I want to be sure. Oh, and now my low side schrader is leaking, I can hear and feel it. Perhaps it was leaking before, but the cap and inside are dry.

Has anyone seen these kind of readings before??

TIA

 

That is excessively low, and why the compressor won't engage on it's own. Yes, you have a leak somewhere, If you already know the valve is leaking, vacuum the system down, and replace it. Then, vacuum the system down again, and leave it for a while, make sure it HOLDS vacuum. Then you can recharge it.

 

Exactly what HeyYou said, I'll add if you vacuum the system down and replace one valve you might as well do both.

 

Yup yup. Replacing o-rings wouldn't hurt either. (here, let me spend some more of your money...... )