Mitsuba 7001 32 0x17 Relay Diagram

Hello,

I would like to ask you for a comment on an aircon oil topping-up.
I spent this weekend browsing the forum and the net, but couldn't find anything, so I decided to ask you on this forum and write the following description.
Perhaps my experience and your comments can be useful to others too. I hope this is the best thread to put i in.

It started during last few kilometers on the way home when an output from ventilation openings turned freezing cold.
Afterwards, the compressor relief valve blown out some refrigerant media several times.
Apart of the hissing sound we observed some smoke and smell of oil mist when we were driving slowly or were waiting on a crossing.

At home I found that the space around the compressor is oily.
Contacts inside the clutch relay are welded together causing permanent powering of the clutch, even when the ignition is off.
This can easily drain the battery flat over night - at 12V the current into the clutch coil is about 3,5A.
At approx. 14V (engine running = charging the battery) the current into the clutch coil is about 4A.
The relay winding resistance is 135Ohm, which is fine, considering the current hot weather.
The resistor inside the relay is burned and all metal parts are corroded, especially the contacts.
As the relay enclosure is air tight, I guess that gaseous product of the burned resistor lacquer was corrosive enough to make the relay to fail.
I would say that the relay is too small for the task. Rated switching current can be 20A or even 30A, but this pays for a room temperature (20°C).
At higher temperature the switching capacity goes quickly down. The current through the winding and the resistor produces about 1,5W of heat.
I would be curious what is the temperature inside the relay during the work. There is a reason for the resistor to have burned lacquer layer.

Also, I do not understand why is the relay contact powered even when the ignition is off. I will have to check schematics, if I find them somewhere.
With welded contacts left unnoticed you can either drain your battery, or burn the compressor. Nice.

I can speculate that with the permanent run of the compressor the expander valve got frozen, and overpressure in the compressor opened the relief valve.

I hope that apart of the oil dispersed around the compressor and some missing refrigerant medium there is no other damage on the aircon system.
I am going to replace the faulty Omron G8HL-H71 relay with the Mitsuba 7001 relay, this is easy.
I also need to recharge the aircon circuit with the refrigerant media. And here come my two questions.

1. How critical is to use by the workshop manual recommended SANDEN SP10 oil,
and not a generic aircon PAG oil offered by a aircon garage to top up the oil in the aircon?
I hope that a decent quality PAG oil with kinematic viscosity @40° = 46cst could suffice,
as I could not find a place selling the SANDEN SP10 oil.

2. What is the proper procedure to achieve the right amount of oil in the aircon circuit?

As I understand there is no way to extract all oil out of the aircon circuit, and put a new oil filling in.
To run the compressor with too low oil level is bad, for sure. What if there is too much of oil in?
How dangerous it is to the aircon system health? What should I do?

Grazie mille
Martin

Posted by: amandadecommandoao.blogspot.com

Source: https://www.civinfo.com/forum/bugs-faults-irritations/73473-updated-air-con-compressor-relay-prevent-failure-32.html