Integral multi driving me nuts!

[Clk320_Greg]

Dealing with a Norpe integral multi dec, about a 2.5M dec. The one with the two compressors underneath and well known for bending pipes and kinking cap tubes when you pull the condensing units in and out...

Anyway the fault:

Call to site as we had an error 6 (Liquid line too hot, at or above 55C). Had a look and cleaned the coils (nothing really comeing out - serviced only 2 months prior) fans all fine. This was on a hot day so reset and returned the next day when it had done the exact same fault. Guages on (low side only as no hp port fitted - yet) we had a suction of 52PSI or -8. So start gropeing the system and sure enough when its all up and running we were getting a red hot coil and liquid line, now the cap tube was fitted directly into the outlet of the drier so i started to look at the drier suspiciously... Check back throught records and found that the system has had a new comp fitted (by another firm) but the drier appeared to be as from new.

So next we changed the drier, and at the same time put a HP access port in. She then ran fine for about a week before again throwing the same arror 6 with a red hot coil!

Thinking that maybe the drier had blocked again we returned to change again (this time armed with a slightly larger drier incase there was a bit of crap we needed to get out) We also left it to vac for near on 24H(with a few visits to release vac with OFN and vac back down). When installing the drier this time we also blew OFN through all sections of the system to ensure ther were no blockages - it all seemed fine.

All back together and weve got the exact same problem!!!!

Were chargeing according to manufactures spec (with a larger drier we may be slightly under charged, but really only very slight) and we are getting LP as before
52PSI or -10 and a HP (taken after the drier before the captube) of 350PSI which gently rises to nearer 400 before shutting off.

As i say the fans are ok, nothing around the unit (boxing in, air flows) has changed but were still getting this HP problem??? Im starting to look at the compressor but can really see how a comp fault could cause this?

Any ideas? (other then replacement of the entire god dam unit)

Thanks,

[Gary]

Hmmm... I'm guessing R404a?

What are the air on/air off temps?

[Tayters]

What's the airflow like through the condensor?
It may look clean but there could be dust stuck deep inside the coil. A good test is to hold some paper infront of the coil. It should get sucked straight on. Sometimes you find certain places (around the edges) where there is poor airlfow and the paper either falls off or doesn't get sucked on as good as it should.
Either way I'd blow it out with OFN anyway. Bound sure to get some crud out.

A blocked drier would cause more subcooling and probably a temperature difference across the drier. Also the evaporator would be starved causing less heat to be absorbed in turn causing less heat rejected by the condenser in turn causing lower temperature of the liquid line.
Evaporating temperature would seem right for a chiller. All in all no blockage.

High discharge pressure caused by poor rejection of heat from condenser it would seem. Also worth checking where the air gets blown to as some integrals get pretty well boxed in!

Cheers,
Andy.

[Clk320_Greg]

Will go back today to get air temps,

It is quite boxed in - but has been since installation so cant really use that as a reason

Report back soon!

[simon@parker]

hussman made a carnousite unit 2 comps under it used to run with massive head pressure and comps would fail it comes down to crap in cappillary lines if it has run with only one comp the oil actually burns and clogs cappillary lines u change drier all is good for a bit had it loads but back then the comps would fail and would be changed i did loads on one unit before penny dropped as to underlying prob change cappillary lines or remove comp and flush system have a look at yr unit and see wot ya think took me a while to get my head round it especially when you have blown nitrogen through it an it clear also check to see if condenser fans are original spec that compounds the problem