i have a 2001 Ram 2500. Over the summer i overhauled my motor. I had the a/c system discharged before i started. When i had it apart i had all of the open lines plugged or capped. I dont pretend o know a lot about a/c systems but I know enough to understand and talk about the system. After i got the truck back together i had it recharged and i had them pull and hold vacuum for 25 minutes and it held no problem. it worked great the remainder of the summer and fall. now im starting to notice issues, first thing i noticed was that the condenser get burning hot almost instantly. like so hot you cant touch it. I noticed that about 3 weeks ago. the other day i left my truck idle while i went into the store (10 minutes) with the defrost on. when i came back out i was just starting to pull out and all the sudden the the pressure relief valve popped open for a couple seconds then it did it again about 10 seconds later and i shut off defrost and it stopped. it did that again when i forgot to shut off defrost when getting subway the other day. then today i turned it on and was feeling around what i assumed was the orifice tube (behind passenger battery) and it was burning hot on one side and barely cool on the other, and then suddenly it popped off pressure beneath the accumulator somewhere. my current thoughts are possibly it got contaminated while apart and the orifice tube is clogged up or the high pressure switch is bad???? Im not sure how exactly to diagnose and i dont want to throw parts at it. any insight is appreciated! thank you

I'm no expert but it sounds like you might have something clogging the system.  Do you have a gauge set to check the high & low pressures? That could tell you if you have a restriction.

 

L8tr

d

9 hours ago, SilverMoose said:

I'm no expert but it sounds like you might have something clogging the system.  Do you have a gauge set to check the high & low pressures? That could tell you if you have a restriction.

 

L8tr

d

No I don't but I was going to ask around on Monday.. But I also have not done anything with a/c since school 7 years ago, so idk what I'm even looking at on gauges anymore lol

I've seen this on 3rd Gens where the fan clutch doesn't lock and the condenser gets extremely hot and the hi side pressure are reaching 400-450 PSI and then purges excessive pressure out the back of the compressor. This can happen on a 2nd Gen truck if the condenser is plugged up and the air isn't flowing well through the radiator and condenser. I've seen this happen when people slide cardboard in between the condenser on the radiator attempting to build heat then run the defrosters and get the same blow off because the condenser can't waste the heat. Another one that will produce the same problem is excessive oil charge from using Quick Cans of freon with the little gauge and hose. Those happen to have a shot of oil in the can and if you use these to often the system will be over loaded with oil causing the same blow off. 

 

So everyone is right take the time and hook up a set of gauges. I would consider changing the orifice tube its cheap. It could be the filter is plugged up.

     If the A/C is working and the over pressure blow off valve opens only when the truck is stationary with the engine on then I think you have an air flow over the condenser problem like Mike said.  You still want to put a set of gauges on and check the pressure.  

• Install A/C gauges and record static high and low pressure along with air temp.
• Start engine and turn on A/C with fan speed on high,  after 1 minute record pressures and center duct temp.
• Montour pressures and temp for up to10-15 minutes.
• If high side pressure goes up to 400+ psi and low side goes to 0 psi or into a vacuum in the first 1-2 minutes then there is a blockage in the system and it is most likely at the expansion tube/valve.
• If the high side pressure goes up slowly and gets close to 400 psi put a large fan, set on high speed, in front of the condenser.  If the pressure come down to normal then there is a fan clutch/air flow over the condenser problem.   

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/54_cab-interior/basic-air-condition-repair-r485/

 

  

Thanks for the info fellas!  I think I can handle that! 

I just don't know enough about this topic to diagnose without some help!

8 hours ago, Dodgeih said:

Thanks for the info fellas!  I think I can handle that! 

I just don't know enough about this topic to diagnose without some help!

Once you get some time under you belt with an ac system, you will figure it out. To me it's fairly basic but has a bunch if parts.  High and low side pressures are the storytellers of the system.

 

L8tr

d

1 hour ago, SilverMoose said:

Once you get some time under you belt with an ac system, you will figure it out. To me it's fairly basic but has a bunch if parts.  High and low side pressures are the storytellers of the system.

 

L8tr

d

Yeah it's already coming back to me in the short conversation here