AC Not Working at Idle

I had to jump my low pressure switch last week. Finally found my extra one under the bunk, amidst a pile of parts, Lol. I was wondering though about him jumping the wire on a double switch, I wasn’t sure,I’ve never jumped that one. good to know anyways. At least he can tell if it’s the switch or not.

 

you got to gauge it

 

Not really, if it was working fine, and has no leaks.And switch replacement fixes problem. It should be fine. One thing at a time. Leave that can of worms closed, unless it doesn’t blow cold. Soon he will be an expert at diagnosis A/C. Problems.On Trucks it’s an annual thing.

 

Figure out what engages the fan clutch. Last Freightliner I had it engaged when air was taken away. If you hear a small pfft when you turn key off, then you may get away with unplugging the fan solenoid. It may through a code though.

 

at the end of the day, he has a leak, putting gauges on it is the sure fire right way. soon he will know

 

DO NOT EVER jumper the low pressure switch.

You'll fry the compressor if the pressure is too low.

FIRST THING to do is check the freon with a gauge set. NOT those cheap arse cans at the truckstop. Make sure your freon is fully charged.

When you're running down the freeway the engine spins much faster changing your pressure over what it does at idle. When you check your freon. ALWAYS have the engine running at high rpms. Because your engine spins most of it's time at higher rpms. And if you need a topoff. It'll happen A LOT faster.

With them big fans pulling in all that air. You should have a high pressure reading of around 150 with a low of around 35ish.

Also make sure your condensor is washed.

Another problem is usually the expansion valve. I see those going bad more and more these days.

 

Amazon has some decent gauge sets for under a hundred bucks.