Pressure to test evaporator

[Z2TT]

Hi,

I have three evaporator cores that need to be tested for leaks.

What is a safe pressure to test an evaporator at for a automotive application. I dont want to put so much pressure as to bust the core.

Can the test be done with the TXV Valve connected?

Thankyou.

[monkey spanners]

I would look up the maximum temp your car is likely to see on a hot day and look this up on a pressure temperature chart for the refrigerant used and go a bit lower just in case.....

So about 110/120psi for R134a

TXV should be ok with this. The other consideration to over pressure is the shaft seal on the compressor and this should be ok also.

[Z2TT]

Hi,

Allthough 120 PSI or more Might be what my car will see on a hot day, would that be for high side or low side, because I believe after the TXV Pressure drops a lot before going into evaporator, So I would like to know what pressures the evaporator would usually see.

I wouldn't believe it would be 120 PSI as isn't that ussually what the high side temps are? From the following page
http://www.aircondition.com/tech/questions/82/ I have gathered that the low side will be around 30 PSI, but i'd like somebody to confirm if its true or not.

I checked the user manual for my car and it says 30 PSI on the low side is acceptable, this is for R12. I am using a hydrocarbon gas (butane and propane) so I believe it should be around about the same. So for that reason would it be necessary to pressure test the evaporator at 120 PSI, wouldn't that cause damage since the evaporator doesn't usually see these pressures?

Also I dont understand why so many a/c places pressure test the WHOLE system at about 200 PSI, when individual areas dont even see that pressure like the evaporator.

Thanks.

Thanks.

[sedgy]

110 percent of the normal standing pressure would be adequate to pressure test,

[monkey spanners]

When the system is off every part of the system will be at the same pressure, it will equalise through the TXV and the compressor after a time.

[Z2TT]

When the system is off every part of the system will be at the same pressure, it will equalise through the TXV and the compressor after a time.

So are you saying that when the A/C Operates, allthough the high/low sides will have different pressures, when you shut the A/C System off all components (even evaporator) can have pressures as high as ones usually found on the high side?

Thanks.

[monkey spanners]

You would need to look up the pressure on a pt (pressure temperature) chart.
So for example at a temperature of 35C R12 would be at 108 psi.

[Tycho]

So are you saying that when the A/C Operates, allthough the high/low sides will have different pressures, when you shut the A/C System off all components (even evaporator) can have pressures as high as ones usually found on the high side?

Thanks.
what he's saying is that if you shut down the system for some time, the pressure in the entire system will equalize to the pressure corresponding to the ambient temperature.

say R-22, if it's 0 celcius outside and the doors are left open to the cargo hold, the pressure in the system would be 4 bar as long as there is liquid somewhere in the system

[Z2TT]

Thanks for the replies.

Should 120 PSI Be a good Pressure to test at?

[Peter_1]

That will be fine 120 psi

[Sheeque09]

You can test it with the fuel pump on, just block off the pulse nipple and install the pop-off pressure hose to the fuel inlet nipple on the carb.

[Peter_1]

You can test it with the fuel pump on, just block off the pulse nipple and install the pop-off pressure hose to the fuel inlet nipple on the carb.

Are wee talking about the same refrigeration system here?
Carburetor :D:confused::off topic:

[monkey spanners]

Friend of mine was pressure testing a car, heard an odd grurgly noise from the back and went to investigate, sounded like it was coming from the petrol tank :confused:

Turned out to have a R134a style connector in the fuel line......

[cadwaladr]

yep been there on a renault trafic van,but it was the power steering fitting whoops????