identify these AC service ports

[philip j]

Are these the factory R12 A/C service ports on my 87 - 930? Or have they been refitted for 134A? thanks Philip

[pochejp]

134a without a doubt. Thats good news for you. The convesion is complete.

[philip j]

Originally Posted by pochejp

134a without a doubt. Thats good news for you. The convesion is complete.

So after reading multiple posts looking for this info, what's the best product to use to top off the system. Seems most are better than the 134a! Philip

[pochejp]

Any good plain 134a WITHOUT sealant added to it. Read the can and make sure its leak additive free because most come with that additive. DuPont brand is what I use when I can find it. It's all the same as only a couple of companies manufacture that stuff.

[kuehl]

The issue with "topping" off a system is you don't know how much refrigerant is in the system, or how much air is in the system (you don't know how well the previous job was done). Many DIY's take a shot at topping off a system because its 'cheap'. But, you don't know what you got in there so 'cheap' is what you are going to get, so its a 50/50 crap shoot; you will need to charge by P&T (pressures and temperatures) however if you have air in the system you will get a false reading.

Ideally you want to evacuate, charge and test. And since you don't know how much refrigerant oil the system lost over time ... that becomes an issue. If you are lucky there will be a blue R134a conversion sticker in the engine compartment telling you what kind of oil was used (you don't want to mix Ester and PAG), or you can check the previous repair orders. As well, try to determine how old the receiver drier is, and put a cap on that bare high side service port.

At some juncture, unless you fix the leak, you are going to be constantly running the compressor into the ground with low system pressures (the system needs sufficient refrigerant flow to move the oil through the compressor to keep it lubricated). A worn out compressor will toss contaminants (metal particles) into the system. That turns into a very costly repair.

Ditto on the "no sealants or additives". Sealants can damage a system.

A low pressure cut off switch, or preferably a binary (low high), will help protect the compressor (they did not come installed from the factory).

[pochejp]

Originally Posted by kuehl

The issue with "topping" off a system is you don't know how much refrigerant is in the system, or how much air is in the system (you don't know how well the previous job was done). Many DIY's take a shot at topping off a system because its 'cheap'. But, you don't know what you got in there so 'cheap' is what you are going to get, so its a 50/50 crap shoot; you will need to charge by P&T (pressures and temperatures) however if you have air in the system you will get a false reading.

Ideally you want to evacuate, charge and test. And since you don't know how much refrigerant oil the system lost over time ... that becomes an issue. If you are lucky there will be a blue R134a conversion sticker in the engine compartment telling you what kind of oil was used (you don't want to mix Ester and PAG), or you can check the previous repair orders. As well, try to determine how old the receiver drier is, and put a cap on that bare high side service port.

At some juncture, unless you fix the leak, you are going to be constantly running the compressor into the ground with low system pressures (the system needs sufficient refrigerant flow to move the oil through the compressor to keep it lubricated). A worn out compressor will toss contaminants (metal particles) into the system. That turns into a very costly repair.

Ditto on the "no sealants or additives". Sealants can damage a system.

A low pressure cut off switch, or preferably a binary (low high), will help protect the compressor (they did not come installed from the factory).

All good points. Without gauges you really don't know what the system is doing. It is easy to introduce air into the system if the proper purging of the hose you will be connecting to the system. Water (air) and 134a mixed can and will create acid that will destroy the whole system.

You would assume that if the system has been converted to 134a from R12 that all the o-rings have been replaced as required. The drier should have been replaced as well as the system cleaned of the old oil and replaced with PAG oil.

If you're not familiar with an a/c system, which I assume you're not by asking about fittings, I would have a shop look at it or top it off for you. JMO

[philip j]

Thanks for your input guys, all very good tips. Philip