Aircon Compressor Problem

Tony Hunt · 08-20-04, 06:17 AM

I am having problems with the compressor on my aircon system.
When the magnetic clutch engages, there is sometimes a loud noise, as if it is only partially engaging and the two parts of the clutch are skipping over each other. At other times, the mag clutch engages with just a click. The bad noise has been getting worse and more frequent of late.
I think that there is something preventing the clutch from engaging fully - is there anything that slides into engagement that could be sticking? My compressor is a SANDEN SD7H15.
How can I fix the problem? Should the pump pump gas or liquid? Is there a possibilty that there is some sort of hydraulic lock in the pump when it starts up?
Is the pulley/clutch dismantleable? Are parts replaceable? Do I have to buy a new pump?
The car stood for some 8 years before I bought it and only covered 1500 miles during the period - the refrigerant had all drained away and the system was pretty clogged up.
Any help, particularly from anyone familiar with the Sanden pump, would be much appreciated.

Trevor Booth · 08-20-04, 06:32 AM

Tony,
I am not very familiar with the sanden pump. Most pumps have a plate type clutch working on the same principle as your engine clutch. The symptons are consistent with stuck vanes. This does occur wherein a pump has not been used on a regular basis. I would suggest dismantling the pump, it is probably stuffed. Hope this helps
Trevor

**candc** · 08-20-04, 03:43 PM

tony
looking in a delphi catalouge at work found your type of compressor it is a r134a type gas it could possibly have either a twin poly v belt or multirib fan belt and either pipes exiting from the rear or top the compressor looks as if it would come apart whats inside i,m not sure we stock them in our parts department their shoul be a build code/ manufacture number on the unit either 7851/7849 (poly vee belt) or 7850 (multi rib) if your interested in a price of a new one the two poly vee belt pumps retail around £400 but we get them for around £220 in vat for the poly vee belt ones and about £200 for the multi rib belt pump.if i can be of further help give me a call at work on 0116 2600625 or pm me
hope this helps chris parker

Jim Dewar · 08-20-04, 10:06 PM

Tony,
There are several possibilties.
(1) the electro magnetic clutch could be getting weak (some clutches can be shimmed to a closer clearance)
(2) check head pressures. If the system is overcharged or the expansion valve is clogged with debris, this will build excessive head pressure causing the clutch to slip.

Tony Hunt · 08-21-04, 07:12 AM

Thank you for your replies, gentlemen.
Chris, the Sanden website has comprehensive parts lists and a manual for the pump. Sanden are in Basingstoke, which isn't very far from here, but if you can source cheap parts, I may well call you. Thank you for your offer.
Jim, you may have put your finger on the problem. Some 2 or 3 months ago, I posted that my expansion valve was found to be partially blocked when we recharged the system after the car had been standing for a year or so. It could well have become more blocked and be backing up liquid into the pump. Is it dangerous to carry on using the system until I can get it fixed?
Time to talk to the aircon man, I think!