My 1996 dodge Cummins AC was working just fine right to the last little cold front we had.

The compressor is turning on & off. I don't recall if it is cycling quickly or normally. I got a can of AC recharge & the little gauge showed that it's full.

I have a set of manifold gauges shipping to me next week. I understand I can tell if the compressor isn't "sucking" enough by what the gauges read. I have a vacuum & waste cylinder to evacuate the system into & see if it holds vacuum.

Can anyone expound on the process a bit for me?

will.mcg said:

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My 1996 dodge Cummins AC was working just fine right to the last little cold front we had.

The compressor is turning on & off. I don't recall if it is cycling quickly or normally. I got a can of AC recharge & the little gauge showed that it's full.

I have a set of manifold gauges shipping to me next week. I understand I can tell if the compressor isn't "sucking" enough by what the gauges read. I have a vacuum & waste cylinder to evacuate the system into & see if it holds vacuum.

Can anyone expound on the process a bit for me?

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https://www.autozone.com/diy/climate-control/how-to-recharge-car-ac

Use the pressure chart at the bottom of the link that shows different ambient temperatures.

Check the area between your radiator and condenser for garbage/leaves/dirt.

That's handy. Thanks!

What's the actual issue? Not cooling or not cooling at certain times?

I generally do it in the morning before it gets all hot.

Slap some gauges on it

Not cooling at all

Gauges aren't going to tell you whether the system is full or not. You can have somewhat normal pressures with a low or high charge. Too much refrigerant is just as bad as too little.

My F250 had normal pressures. I threw it on my refrigerant machine last week and pulled out .6lbs refrigerant more than spec.

Orifice tube seemed to be clogged.

will.mcg said:

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Orifice tube seemed to be clogged.

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Just a lil bit.

Is there a way to tell from the gauges if the compressor is sucking enough? It froze me out for a week or so now I'm experiencing the same problem I started with. When I vacuumed it down it held vacuum so I doubt there is a leak.

will.mcg said:

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Is there a way to tell from the gauges if the compressor is sucking enough? It froze me out for a week or so now I'm experiencing the same problem I started with. When I vacuumed it down it held vacuum so I doubt there is a leak.

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When you found the junk in the orifice tube what did you do to clean out the rest of the system?

I thought I saw metal shavings in the picture which means there more than likely was more floating around....

Oh clever! Answer a question with a question! I blew what lines were open with compressed air. It may be bad information that I believe the accumulator catches trash.

seeing the orofice tube looking like that, your compressor is trashed.

That was my first inclination but it seemed to be "compressing" still. It is 5 years old so I suppose that is a pretty good life span.

will.mcg said:

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That was my first inclination but it seemed to be "compressing" still. It is 5 years old so I suppose that is a pretty good life span.

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If it's low it will still compress. When it hits a certain threshold the low pressure switch will cut power to the coil.

What am I going to damage if I override the pressure switch?

will.mcg said:

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What am I going to damage if I override the pressure switch?

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You'll burn it up.

The pressure switch isnt kicking in right now.

Its marginally low and not getting enough high pressure to pass through the orifice and cool properly.

I'm almost willing to bet that topping it off will get you back to normal performance.

I am definitely going to try that. Question is if I don't have a leak am I "overfilling" the system?

will.mcg said:

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I am definitely going to try that. Question is if I don't have a leak am I "overfilling" the system?

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You definitely have a leak. How long it lasts will be a tell tale sign.

5 years with no charge is about the right service life IMO.

My Flex was blowing tepid and I found the schrader valve seals were hard as rocks.

25 bucks for new ones (some silly design that Ford and GM use now) and it was back to nice and icy.

I must have left out that I replaced the accumulator & orifice tube then recharged the system last week. It held vacuum before I recharged it.

If you didn't flush the system out, the trash is there still. And the compressor function is marginal. That material is mostly seal material from the compressor.

Sad part is all that needs to be replaced again when you do the compressor.

I was thinking that. Thanks fully that kit was less than $100 including refrigerant.

1agswitchin4lanes said:

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If you didn't flush the system out, the trash is there still. And the compressor function is marginal. That material is mostly seal material from the compressor.

Sad part is all that needs to be replaced again when you do the compressor.

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When you flush the system, use a compressor nozzle with a pick up line and hit it with liquid brake cleaner. The brake cleaner will get out more than just a shot of air, and it will also dry out without leaving any residue.

I prefer BG Frigi Flush over brake clean.

Brake clean does work, but the affect on seals worries me.

Thanks guys. I will flush it next time I open it up. A new pressure switch has it going again. I hadn't lost any refrigerant since it quit cooling. Hopefully I won't be updating the post with more problems anytime soon.

Where is the best place to insert the compressor nozzle to flush the system?

The next time you open it up I'd
pull the condenser and clean out the junk on the fins and also the radiator.
Flush the condenser by itself
Disconnect all the lines and flush individually
Flush the evaporator core by itself.
Replace the valve guts on your high and low test ports.
Replace O-rings at the connections.

That may be considered overkill but years ago I was surprised at the amount of crap in my condenser.

Just remember flushing EVERYTHING with a chemical flush will remove all of the oil from the system (except from your compressor) so you'll need to add the correct amount back in.



You can also check the prices on a new condenser. IIRC they were < $100

Sweet! Thanks. Yes condensors are still relatively cheap.