A/C system hardly working. Please check my work.

[Stainless]

It's getting kind of late in the year to work on A/C, but I finally had time to try and get mine working. My A/C has not been functional since I bought my car over 2 years ago. I decided to convert my system to R134a the quick and dirty way by flushing the system with mineral spirits, vacuuming the system, and filling with freon. I also want to note that the compressor had zero oil in it when I went to drain it before filling it with ester oil.

Before running a vacuum, I filled up the system with compressed air to test for leaks. I filled the system with around 90 psi of air and tested all of the connections in the system that I could see with a soapy water concoction. My tests came up with nothing. I couldn't find any evidence of a leak anywhere. I couldn't and didn't check the evaporator for leaks.

I then evacuated the air and added some dye to the system to help find any future leaks. I then ran a vacuum for an extended period and then proceeded to add about 2.5 cans of R134a. While filling with the first can, the compressor cycled on for the first time since I have owned my DeLorean. I was relieved that it engaged as I wasn't sure it even worked, especially since it was bone dry and had no oil in it before this process. The radiator fans also kicked on at the same time that the compressor engaged. After filling up with just two cans, the temperature coming out of the vent was only about 60 degrees. I added about a half of another can, but the temperature would not drop below about 58 degrees.

The pressures just did not look right. I expected the low side pressure to be much lower, but it wouldn't go below about 40. This was with the ambient temperature at around 70 degrees. The compressor is engaged whenever the A/C is on and doesn't ever cycle, even when I am going down the road at 45 MPH. In other videos that I have seen, when the compressor engages, the low side pressure gets lower and lower and lower until the low pressure switch disengages the compressor, at which time the pressure rises until the compressor kicks back on again. I am not seeing any reduction in the low side pressure, but it is staying pretty flat at 40 psi. Looking at the ambient temperature/pressure charts, a low side pressure of 40 might actually be what I can expect at 70 degrees, but I would expect the air temperature out the vent to be much, much cooler. I would also expect the low side pressure to go down with time and not stay steady with the compressor running constantly, especially if I am driving down the road.

I took a video of what the system is doing at idle to show you what I mean.

On a possibly unrelated note, when I shut off the car, I hear what sounds like a squeaking noise coming from the evaporator/dryer area. I don't know what it is or if I should be worried about it. It may be the orifice tube allowing the pressures to equalize, but I don't know if it could make a noise when doing this. I filmed the noise and included it at the end of the video below.


http://www.youtube.com/watch?feature=player_embedded&v=Zl68yRi0cDw

Any idea what is wrong with my A/C system? I have received the recommendation to evacuate and flush the system again with mineral spirits, but I'd hate to drain and refill the system only to find out that nothing has changed. The good news is that there was lots and lots of water draining from the evaporator area, which I understand to be a good sign.

[djdogbone]

I did my 134 conversion in two stages. The first is what you did and the compressor died.

The issues with dry systems is that the orifice tube gets clogged http://store.delorean.com/p-7724-orifice-tube.aspx

And the accumulator gets fouled up.
http://store.delorean.com/p-7714-accumulator.aspx

After the system died the first time, new compressor, orifice tube and accumulator I have had no issues.

[Stainless]

I did my 134 conversion in two stages. The first is what you did and the compressor died.

The issues with dry systems is that the orifice tube gets clogged http://store.delorean.com/p-7724-orifice-tube.aspx

And the accumulator gets fouled up.
http://store.delorean.com/p-7714-accumulator.aspx

After the system died the first time, new compressor, orifice tube and accumulator I have had no issues.

But before your compressor died, were you also having issues with the temps not getting low enough? Could a clogged orifice tube and fouled dryer cause the symptoms that I am having?

[Ron]

You said you decided to flush it but didn't mention you actually did?

That looks OK for 70 F, at cut-out. But, never going below 40 psi is a classic sign of; an overcharge; an incorrect, damaged, or mis-seated orifice tube (perhaps the source of the noise...??), etc; or, a weak compressor (High side usually low here).

Sounds like you should drain all of the oil out of it, flush it and replace the orifice and accumulator (dryer), unless it is brand new and hasn't been exposed it the ambient). This way you can check the orifice and know the oil and refrigerant charge are correct as well. (You might want to see that the compressor is capable of high pressure first...the pressure should climb if you add more refrigerant, a waste and a one way test, but it will aim you in the right direction anyway....

FWIW, I hesitate to mention it, but there is a rumor out there :rolleyes: that any obstruction in the system will cause the high side to go high. Common sense will tell you that any obstruction near the suction port (low side) will prevent the compressor from having any output at all in short order. It's the #1 give away for a clogged input screen (when so equipped)...nothing in -- nothing out.

[David T]

You did not say how you "vacuumed" the system. If you did not evacuate it to a low enough vacuum you probably still have air and water vapor in it and that could cause the low side to be high and prevent you from getting enough capacity to cool properly.

[Stainless]

I didn't realize I needed to include every small detail. Yes, I flushed the system with mineral spirits. I used a quart or two and got as much of it out as I could, flushing from the high side to the low side.

I vacuumed it out using a 2.5 cfm vacuum pump down to just under 30 milligrams of mercury, or whatever that measuring metric is. The system was then charged under these conditions. Any other detail that I am overlooking?

[Ron]

You did not say how you "vacuumed" the system. If you did not evacuate it to a low enough vacuum you probably still have air and water vapor in it and that could cause the low side to be high and prevent you from getting enough capacity to cool properly.
Yeah, the high side is on the low side of normal for exactly 70F...but it would be a bit better if it pulled the low side on down to 28-32 I would guess.

[Ron]

I didn't realize I needed to include every small detail. Yes, I flushed the system with mineral spirits. I used a quart or two and got as much of it out as I could, flushing from the high side to the low side.

I vacuumed it out using a 2.5 cfm vacuum pump down to just under 30 milligrams of mercury, or whatever that measuring metric is. The system was then charged under these conditions. Any other detail that I am overlooking?hehe Those are the ones that bite you on the arse. Vacuum is very important and a common problem related to your symptoms, why David hit the idea again I guess... Anyway, sounds like you should be good on the flush, assuming you got roughly as much out of it as you put in and blew it for a little while afterwards. ...I assume you simply put in a full oil charge.

Another important detail- Were the cans 12 or 14 oz? Sounds like 3 cans total, so that would be close if they were 12 OZ cans a little to much if 14 oz. (Not to mention you reduce some with 134a)...

Everything sounds real close here....anything else that might be a clue?

I'm sticking with overcharged or problem at the orifice tube, so far.

[David T]

Another of those petty details is how long you maintained the vacuum. It can take a while to get all of the moisture out. You do not just pull the vacuum and then stuff in the refrigerant. Because you also used mineral spirits there may be some of that also floating around in there that was not vacuumed (boiled) out. By not replacing the dryer it may (and most likely is) overloaded with moisture and can't help. Any system that is at atmospheric for a long time is considered contaminated and the dryer should be replaced. Unless the system was black inside the orifice tube should be OK. It has a large filter on it so it the orifice itself doesn't get plugged up, the filter does. If the system is overcharged the high side would be much higher, especially with -134.

[Stainless]

The cans were the 12 oz R134a cans that Big Lots sells.

I drew a vacuum multiple times during my troubleshooting and conversion process. The period immediately before filling it up, I drew a vacuum for 30 minutes before beginning the process of charging. It's possible that the dryer is not performing up to par. I guess the next steps will be to replace the orifice tube and dryer. Perhaps I'll flush it out once more for good measure, then replace these components so that I am 100% sure that the system is starting clean. I may not have a chance to do this for a couple of more weeks, by which time it may be even cooler here. Hopefully mother nature cooperates and it stays warm enough to do A/C work in late September.

[Ron]

36 Oz is just under the old spec. So it wasn't overcharged in that respect. They lowered it because of compressor noise while cranking. I would shoot for the new spec since you're using 134a and watch the gauges during the last bit making sure you take readings at clutch cut-out and compare to the chart, preferably on a hotter day. Otherwise I would put in exactly what they call for. That way it will be correct for all temps, no box fans, fan speeds, heat transfer, etc to worry about (unlike reading the output temp to charge it).

FYI- 30 minutes is a minimum...OK if you just pop a part off and right back on. I always go 1 hour to give it a chance to boil off any moisture etc, even using a HP pump.
Maybe just semantics, but any moisture the dryer absorbs after evacuation and charging was already in the system...

Yes, a new dryer is a good idea. Forget tales of getting moisture out of them by running a deep vacuum for long periods of time -- The desiccant inside does a good job of locking it in...

Good luck!

[DMCMW Dave]

Any other detail that I am overlooking?

If you flushed it with the accumulator in place, it probably ended up with quite a bit of the mineral spirits inside the bottle.

[David T]

If you flushed it with the accumulator in place, it probably ended up with quite a bit of the mineral spirits inside the bottle.

The proper way to evacuate a system is to use an electronic vacuum gauge and watch it till you get down to 400 microns (can take more than 1/2 hour) 300 is better yet. Lock the vacuum in and it should not go up for at least 5 minutes. If it does it means you still have moisture in the system (or a leak). It is possible to "unlock" the moisture from the dryer by applying heat to it but it is a much better idea to replace it. If you do decide to replace the orifice tube be careful or you will also be replacing the evap coil. A VOV is probably a good idea if you are converting to -134.