Hi ALL,

Need some help from individuals with lots of 700/900 A/C experience...

Just received my tif 6500 vacuum leak detector. Seems to work fine. Beeps around every second and accelerates with vacuum near the tip. `high sensitivity setting`works fine too. I have a mastercool 5CFM pump that is great, and a set of manifold guages.

Anyhow, the 940 volvo was factory converted to r134 around 5 years ago, and 3 years ago I had the high pressure hose replaced.

Cooled very well, now I had a leak. On the mastercool pump at around 28 MHg, the A/C system loses around 1 per hour, went down to 16 overnight. Last month I tried charging it up and it lost the refrigerant within 3 weeks.

I have taken apart and replaced all o-rings at the accumulator area, in/out, fill valve, piping o-rings to evap at firewall. Still the same rate of loss of vacuum (this is the only leak detection method I have now). While under vacuum I checked the lines to/from the compressor, the condensor itself behind the grill, the line connections, around the compressor. No audible (rate increase) vacuum leak with the TIF unit. Am I using this right? I slowly move around the unit's probe, tried to cover as much surface area as possible on the condenser (but can only get the front side). The only place I have not looked is in the evaporator. I am trying to find a leak somewhere under the hood, it's much more typical, evap on 700/900 cars are generally long lasting from what I hear. Plus I would need a day of labor just to open up the casing under the dash... :( Hoping the leak is not there!

Any other checks I can do? Should I assume I should have already found the leak if it was not the evap? Any other way I can test the evap without disassembling the entire casing under the dash?

Any words of wisdom or specific other places to check? Hoping I would not need to get at the evap.

Let me know, thanks.

Greg Mustang