The low and high-pressure switches are screwed onto service taps; they should have a shraider fitting in them. You should be able to unscrew the bad switch and screw the new one on without loosing your refrigerant unless someone removed the shraider fitting in the past.

Neal

 

I will be checking the electrical out today.

On the issue of compressor oil. The compressor came with lubricant in the cylinders. As per the shop manual, you are supposed to add 4 oz of oil to the compressor. Where does this go in and does that involve opening the system? Sorry if these are all stupid questions, but A/C is just one thing I've never put my hands on, so this is ALL new to me. The R134a that I put in was made by Interdynamics and says "R134a & Oil". Do I still need to put oil in?

I have a thermostatic switch. But there is also mention of a "Compressor Discharge Pressure Switch" in the manual. Not sure where that is.

I'll let you know on the switchs.

 

It was a bad thermostatic control switch.

I pulled the leads off the high pressure switch and tested them with a voltmeter, and there was power getting to the switch. So I put a jumper wire between the leads and the compressor didn't kick on, so I figured it wasn't that switch. So, I went and bought a new Thermostatic control switch at NAPA, installed it and it now comes on and blows cold.

Now, my concern is the guy I was talking to at NAPA (not an employee, but a mechanic) was telling me how if you open up the system, and don't replace the accumulator, especially here in Florida, moisture gets in to the silica bag in the accumulator, then mixes with the oil and becomes an acid. So, now I'm thinking I just wasted my time and money, because I didn't replace the accumulator and the whole system is going to be ruined. I did have the system evacc'd out before re-charging, and the air does blow cold, but...

 

tough call, when the e-vac. was done it will pull H2O out of the system
but i don't know if it was enough

 

I mentioned this to you before in another post about replacing the accumulator if the system was opened. If I were you I would just play it by ear or in this case feel. If the system is cold enough for you now that you replaced the switch I would leave it alone. If at some point you feel the air conditioner doesn't seem like it is working up to par then I would consider replacing the accumulator and ortifice tube. If it is nice and cold now like I say leave it alone.

Fred

 

Fred,

Yes, you did mention it before. But, as I am going on vacation next month for my 20th anniversary, and as my wife has already told me what I am getting her for that anniversary, and as that all involves a lot of cash, I was trying to do this as cheaply as possible. If something didn't need to be replaced, I was trying not to. Some people said you had to, others said it wasn't necessary. I guess it all depends.

I just got back from a little run. On Max A/C with the blower on high, it cools enough to be comfortable, but it never got icy cold.

So, it looks like this winter, I will be evacc'ing the system again, replacing the accumulator and the orifice tube, and re-charging. I gave it a shot.

I guess the good thing is, I now know a lot more about air conditioning then I did when I started.

 

79MakoL82,

We have all been there and some of us have learned the hard way. Like I mentioned before I wish I had the information that alot of younger Vette owners are getting on this forum 35 years ago.

You say your A/C is cold but not icy cold. Some A/C units depending on how hot it is out there don't work as well on the hottest days. You are in Florida and if its anything like it has been here in N.J. the last couple of days where you could hardly breath out there some A/C's just don't seem to do the job as well on certain cars. In other words not like the A/C on a brand new car because certain components over time start to go bad like the oritifice getting dirty and an accumulator or dryer starting to go bad or freon leaking out. Try your A/C at night time without the sun beating down on your car to see if there is any difference. Like you mentioned you always have the winter time to do this and in Florida it is probably the perfect time of the year to work on that a/c system.

Fred

 

Thanks Fred.

It's probably about two months here before the weather breaks. So, I'll just use it as is for now. It's better than it was. But now that I know what the accumulator does, I can understand why it would need to be replaced. And as I'll have the system open again, I mine as well replace the orifice tube. What I know now though is, I'll evac the system, change the orifice tube and accumulator quickly and get the system evacc'd again immediately. THEN recharge the system.

Thanks for sharing the knowledge!!

 

The accumulator has a cloth bag filled with absorbent to wick moister from the system in the event that some moister gets into the system while servicing it. When a vacuum is pulled you will never get 100% of the moister out of the system. What is left will be contained in the absorbent bag once the system is service a few times this bag will become saturated and will no longer do its job this is why it is recommended that the accumulator be changed with the comp. If you’re A/C was not worked on more than a few times or left open for to long I don’t think you have to worry about it.

With the A/C on max and the fan on high and the doors closed fill the suction line at the comp is it cold and sweating? How are your seals around the radiator and condenser coil? At idle there is very little airflow across the condenser so the fan is carrying the full load this is when the seals around the condenser and radiator are very important. At speed can you tell if the comp is cycling?

Neal

 

Yes, the line is cold and sweating. There is a lot of condensation coming off the accumulator also. My seals are good all around. The guy I talked to down here basically said, if an accumulator is open more than 10 hours down here, throw it out, it's garbage. In all honesty, I don't know how many times mines been worked on or how long it was open. When I took the compressor out, I tried to plug the lines up, but I don't know how effective I was. So, my guess is, it probably makes sense to go ahead and replace it this winter. That way I know it's all good.

It does feel like it's cycling on and off. Every once in a while, I can feel it drag on the engine.

Again, probably best to just replace it this winter. Then there'll be no worries.

Thanks again.

 

79MakoL82,
Make sure when you change the accumulator this winter that it is one of the last things you do before evacuating it. In other words do the ortifice first and any seals that need to be done. This is the time to replaced the accumulator and right after replacing it put a vacuum pump on the system for around 30 minutes with a set of gauges and then make sure it holds vacuum. Then refill it.

In the mean time now being that your system is still working my suggestion to you would be to go out and buy a A/C thermometer to stick in one of the ducts to see how cold your A/C is really putting out. These things are worth their weight in gold and not very expensive. Get one with a large round dial on it so you can read it better in the car. These things are great when filling the system also. You don't have to just rely on feel if you think the inside of the car is getting colder or not, the thermometer is right there to tell you. I also keep one in my house in one of the ducts for my home central air system. This way I can go over to that duct and with no guessing to check if my A/C system is working properly. On my thermometer there is a shaded area from 47 degrees F to 64 degrees F. As long as the needle goes into the shaded area your A/C is doing its job. If not you know you have a problem.

Short Story: With all the A/C work I have done over the years I never messed with my home central air until this year. My house was built 20 years ago with this system. Anyway earlier during the spring my system was causing a lot of water from condensation to go all over my floor in my basement and didn't seem cold enough. I talked to a few people thinking maybe my system was going bad finally after 20 years. Well I already had a 30# container of R22 that I purchased years ago just in case, got my R-12 gauges and went behind my A/C system outside my house and hooked up and sure enough after all these years I was down a little on freon. In about 15-20 minutes I was good to go after I blew the dirt out of my condenser with my air hose. The house is nice and cold like the system was years ago and hasn't skipped a beat. Having the thermometer in one of the ducts like I mentioned earlier tells me this system is still working find and the needle is still where it was in the shaded area after I refilled it in May.