intermittent clutch binding on sprinter van

[hertfordnc]

First post. so glad i found this forum. I am a marginal electrician and self taught HVAC hack, I can work a vac pump and nitrogen well enough to save some money over the years.

So, I bought this 2006 Sprinter last summer, It has rear AC with its own dedicated compressor. When i got it there was a constant chirping noise. so i changed the compressor. Doing that changed the noise from continuous to randomly intermittent.

So now it will run for a while, blow cold air and then start screaming loudly. The compressor is biding, the noise is actually coming from the belt. It will chirp for 10 seconds or so and then go back to running normally.

So we are clear- there is nothing wrong with the belt or any other moving parts. All my googling came back to serpentine belt or fan. THat's not what happens here.

I watched it happen, the compressor is actually stopping. I cut power immediately and i can feel the compressor bound up. But if I go back sometime later if will spin smoothly,


Low pressure side seems to be about right- 55psi at 85F - it spikes to 65-70 when the squeeling starts, and then goes back down.

High pressure side is around 180 and does not fluxuate. when the noise occurs.

I'd be grateful for any insight, the only reliable service in my area is a mercedes dealership.

thanks

[tbirdtbird]

The comp failed sending debris further downstream to the condenser and further on to partially clog the system and then into the new comp where it has wreaked havoc there, too.

You didn't say TXV or OT.
When a comp grenades, here is the sequence of repair:
1. flush or replace all hoses/pipes. If the evap is easy to get to, remove, and flush that too. If there is a TXV, remove it before flushing. If OT, replace it and replace accumulator. If TXV replace receiver/drier. Visually check TXV for debris, and blow it out with a can of computer air (this is a dry gas and will not introduce moisture)
2. replace condenser, they are not readily flushable...it may seem like it does, but the flush is just avoiding the passages with the debris, which over time will loosen up and get back into circulation.
3. replace comp

[JohnHere]

The condenser also serves as a filter. So any debris shed from the original disintegrating compressor will lodge in the condenser. Some of that debris—usually plastic and metal, plus burned oil gunk—will eventually work it's way downstream to the other components. In this instance, they "found" the replacement compressor and ruined it, too.

Low pressure side seems to be about right- 55psi at 85F - it spikes to 65-70 when the squeeling starts, and then goes back down.

In my humble opinion, the LP side is much too high for any cooling to occur, but it should moderate down to the normal range after you repair the system as previously outlined.