Manually force compressor to engage

[nhudson1]

Having stupidly not noticing the aircon has been off all year, and after a few hours of a "hissing" (noise thru the vents) aircon system it no longer makes any noise, bonus. Although, no noticeably cold air, but it's not exactly been hot outside right now.

Problem, I'm not sure when the compressor clutch should engage, would it engage all the time? Is there an ambient outside temp when it won't engage, so as not to be needlessly using the aircon?

I can see the pulley turning, but the clutch doesn't.

Is this likely to be a low pressure lock out? Can I bypass the relay/fuse to see if it does engage before I spend money out on a regas?

Cheers!

[Steve_D]

There is normally just one wire going to the compressor clutch. Apply +12v to this wire should engage the clutch. Don't do it any longer than you need as the pump relies on the flow of coolant to keep it lubricated.

If you take it for a re-gas ask them to do a pressure test first. They do this with an inert gas and can then work their way around the system listening for the leak.

Steve

[nhudson1]

Steve_D said:

There is normally just one wire going to the compressor clutch. Apply +12v to this wire should engage the clutch. Don't do it any longer than you need as the pump relies on the flow of coolant to keep it lubricated.

If you take it for a re-gas ask them to do a pressure test first. They do this with an inert gas and can then work their way around the system listening for the leak.

Steve

Thanks Steve.

I only had it re-gassed a new condenser fitted April last year, they didn't give me the best feeling that the knew what they where doing TBH, but the aircon did work, then winter hit...

I hear mixed feelings about pressure tests causing false positives, the suction causing the seals to appear to close?

I see there are high-pressure nitrogen leak tests, but that's extra in cost to the re-gas itself.

[E-bmw]

I think as F-gas is very heavily governed & it is illegal to knowingly gas a system without first checking for leaks I think you will find a vac test, then pressure test are mandatory prior to re-gassing, so it should be included.

[nhudson1]

E-bmw said:

I think as F-gas is very heavily governed & it is illegal to knowingly gas a system without first checking for leaks I think you will find a vac test, then pressure test are mandatory prior to re-gassing, so it should be included.

The guys that re-gassed it last time, it was empty, had real issues filling it back up, but once the machine was hooked up they're off doing other things.

Halfords do a £40 nitrogen leak test, in addition to the £40 vacuum and leak test when it's being charged by the machine. Apparently the high pressure nitrogen is more of a audible test than relying on the machine.