View Full Version : Oil differential switch trip time?

monkey spanners
18-05-2013, 01:36 PM
Got a Daikin UAT30HY1 that i found tripped on oil pressure, CCH is ok.

Once reset you have to turn it off and on in the plant room and then walk back outside to see if it started ok. First time it had tripped before i got there, so i reset it but waited 30 minutes as i worked on another system just incase there was any heat still in the bimetalic trip mechanism.
This time i timed it and it tripped again in under 30 seconds. You can see the system is building oil pressure as 'pointer' on the bellows starts to lift off its stop but not quite enough to drop the heater out of circuit in the 30 seconds or so.

I poked a screwdriver in to lift the pointer to the ok position and when i checked it at about a minute it would stay there.

I did not get to check the oil pressure :o as had four of the things with various faults and this one wasn't a priority.

Right finally to my question! How long should the oil diff switch wait before tripping? Thought they were 120 seconds but am not that familiar with them tbh:D

The systems and 20 ish years old on R22 and 4GS mineral oil. I doubt the oil has been changed since new.

install monkey
18-05-2013, 02:15 PM
penn oil press diff switches typically 90-120 seconds- check the heater on the switch is only powered once the contactor for the comp is eneregised, if theres a 3 min anti cycle on the pots then that could be affecting operation

18-05-2013, 02:49 PM
Hi MS sometimes you just need to make the time and sit there to make the measurements to be sure if it is the oil pressure or the safety device. Spot on IM from above post.

install monkey
18-05-2013, 02:50 PM
no mention of oil press switch

18-05-2013, 03:23 PM
switch off compressor supply keeping control circuit powered and reset the switch after its cooled,then watch + time it ,then you should know the time out

monkey spanners
18-05-2013, 09:14 PM
I checked the heater supply, its run off the compressor contactor so is only powered once the compressor is running.

I'll have to try Daikin :rolleyes: for info on the delay (Climate list a range from 0 to 120 seconds so could be any in that range or even a special i supose) and the correct oil pressure for their compressor

18-05-2013, 10:19 PM
disconnect the compressor supply ie the breaker to the compressor then dry run it keeping the control circuit powered.

19-05-2013, 01:26 AM
You could remove the lines and test the switch with Nitro if not too much hassel. If you can't get the oil pressure ratings I normally go off a similar size compressor on the same gas.

monkey spanners
19-05-2013, 12:59 PM
Theres no service valve on it and holds about 15kg... Think its about 80kw duty, the compressor is a big 8 cylinder job with two unloaders.

This is the type of system,


install monkey
19-05-2013, 02:51 PM
technical manuals for this jobbie- no service manual- forbidden 404!!!!:)

install monkey
19-05-2013, 04:26 PM
shows all sanginomiya oil press switches- my work here is done!;)

20-05-2013, 02:20 AM
Wow MS very cool Youtube clip and gauges. That size I would guess at 25 PSID Minimum (probably normally around 60PSID)after 120 secs (or longer) going off a similar size york 8 cylinder. From experience I have had few OP SW fail - mainly found SOG and Lo loads logging oil in cooler.

monkey spanners
21-05-2013, 10:50 PM
Thanks IM and Tesla!