Air con pressure

[john2443]

DAK what the high pressure side of air con runs at?

Not the pressure you need to put in when re gassing, the pressure when it's running.

Why am I asking? I'm trying to repair a leaky joint and need some idea of what pressure to test it at before I put it all together and take it to be regassed. I know they'll test it before putting the gas in but I don't want to re assemble it, put the air filter and all sorts of other stuff that gets in the way back in and then find it leaks and I have to dismantle it all again.

Thanks

[Layacable]

When pressure testing an air con/refrigeration unit etc, we normally go by the rule of test up to 1.2 x the maximum working pressure of the system ( so if the maximum working pressure is 100psi, test to 120psi)

[sassanach0]

on a car ac system it can reach 350-400 psi before the pressure switch kicks it out,on a very hot gridlocked motorway with a naff condensor fan normally 150 to 200 psi

[john2443]

sassanach0 said:

on a car ac system it can reach 350-400 psi before the pressure switch kicks it out,on a very hot gridlocked motorway with a naff condensor fan normally 150 to 200 psi

OK, thanks, don't think my compressor will get that high, but it will give be an idea if it's worth assembling and testing it.

[Matt Seabrook]

Don't use compressed air to test an A/C system. Use nitrogen

[john2443]

Matt Seabrook said:

Don't use compressed air to test an A/C system. Use nitrogen

Why? Is it because of molecule size or dryness?

I'm not going to do any damage as I'm just going to test the joint between the old dryer and a pipe before I get the new dryer and assemble the whole lot.

Thanks

[jeebus]

john2443 said:

Why? Is it because of molecule size or dryness?

I'm not going to do any damage as I'm just going to test the joint between the old dryer and a pipe before I get the new dryer and assemble the whole lot.

Thanks

Dryness mainly,Moisture in an ac system causes major problems and turns the oil acidic and will cause problems when you vac the system out, you will struggle to get enough pressure into the system with an air compressor to correctly strength test it, also the refrigerant pressure is worked out by temperature not the compressor output R134a will be at 147psi at 40oC.

Also if you do decide(and you would be foolish to) to put air in the system, do not start the car as you could destroy the compressor fairy quickly.