A/C Help!!!

[pedro]

My A/C sometimes will work and sometimes will not work. The A/C clutch would sometimes not engage. Is this a common problem with 1991 240sx (coupe)? Is there anything that I should check? Any help will be appreciated.

[mrbizness1]

If the system is low on freon the clutch will no always engage depending on the outside temperature. Have the freon checked first.

[pedro]

Thanks for the reply. What would be the pressure to say that I have enough freon?

Thanks,Peter

Having R134a in the system will not help, correct?

[benemorius]

Thanks for the reply. What would be the pressure to say that I have enough freon?

It varies. If you're thinking of getting one of those useless diy gauges and checking the pressure yourself, don't bother.

Having R134a in the system will not help, correct?

What do you mean exactly?

When it does work, does it work normally?

[Q45tech]

The charge must be recovered and weighed via the AC machine.........even 3 out of 32 ounces is significant!

[Q45denver]

Will the machine also remove the oil when flushing the system or do you have to drain it out manually? I assume the receiver/drier will be changed.

[benemorius]

Will the machine also remove the oil when flushing the system or do you have to drain it out manually? I assume the receiver/drier will be changed.

You will still want to drain and flush the system if you expect to get all the oil out. Mind you it is not possible to clear out all the remnants of everything. If you think you can get things sufficiently clean to use PAG oil in a system which previously used R-12, you're DEAD WRONG. There will still be plenty of chloride compounds remaining to destroy PAG oil.

The drier will be replaced if you know what you're doing.

[pedro]

It varies. If you're thinking of getting one of those useless diy gauges and checking the pressure yourself, don't bother.

I put 2 cans of r134a that I bought from WALMART. It is 32 oz. per can. The gauge (which is from WALMART as well) tells me that it is overcharged but as you mentioned, that is not accurate at all.

What do you mean exactly?

When it does work, does it work normally?

I filled with r134a without doing any conversion of the fittings. It works in the morning and in the evening when it is not too hot. During the day, it does not work at all.

[benemorius]

You might have mentioned such minor details from the begining. I hope you're wrong about putting 64oz of refrigerant in. To call that too much would be a gross understatement. There are a number of reasons it doesn't work. Because you didn't replace the drier. Because there is too much air in the system. Because there is too much water in the system. Because your compressor is upset at not having any oil. Because there is too much or too little refrigerant. A/C isn't something you can do yourself unless you know what you're doing. Take it to someone qualified or kick back and prepare to do a lot of research.

[Touchdown038]

I totally agree with benemorius, A/C isn't one of those things you can just throw it all together and have it work well. You really have to have the proper tools and know-how, otherwise you're just wasting your money. Speaking from experience, it's better to take the money you would have spent on new parts and refrigerant and use it to pay someone to do it right.

[Touchdown038]

Oh and I really hope you had the system flushed and the R-12 pumped out before you put in the R134a...