ARRGGGH! Another Compressor won't engage post!
 

Yep, another compressor won't engage post.

New parallel flow condensor (original condenser sprang a leak). More oil (150 ml - 50 for each of the condenser, drier, lines).

Vacuumed to 26 mmHG for 2 hours, and recharged with equivalent of 3 lb R12 with Envirosafe R12. Low and hi side are 75 PSI. But the compressor won't engage.

I shorted the pressure and temperature switch and the aux fan and compressor wouldn't switch on. Fuse 8 (compressor) is good.

What the hell is going on? Why won't the aux fan switch on? Geez, I thought I knew what was going on with the AC on the W123.

Pissed off.

Is this the 240D? Check the relays under the black cover on the left fender in the engine bay. Both of those are involved in the operation of the A/C compressor clutch.

Yep 240Dt like yours, same year
 

Yep 240Dt like yours, same year.

Thanks for the reply.

but why would the relay be blown when everything was working fine before the condenser blew? The compressor would engage before the replacement.

Anyway, how do I check the relays?

I hope you don't really mean 26 mmHg as that is very little vacuum. 26 inHg is more believable, but still not good enough to boil off the water in the system. Of course, that isn't your problem with the compressor not starting. It will just shorten the life of the parts once you do get it going, regardless of what EnviroSafe tries to tell you.

The relay would be blown potentially because it sat not moving for a while, and seized up randomly?

Jump the compressor clutch. The wire with the brown stripe is -, the other is +. (although reversing will not hurt it if you just do it for a second) directly to the battery with a switch. When the switch is engaged or you hold the terminals together at least, the clutch should click into place. It could potentially have failed.

If the A/C cools with the clutch jumped, then it's something further up the chain. If you're sure the evap. temp, pressure and temperature switches are good, as is the "compressor wanted" switch in the cabin, then it's a relay.

Search for the W123 240D A/C FSM, one of the pages selling it has a copy of the circuit wiring diagram. I own a paper copy but no scanner.

Matt, yes, I meant 26inHG. I thought the standard vacuum was 27inHG for an hour? So considering it is about 90F here, I thought that would compensate....:(

JKoebel - Thanks, I have the FSM, I 'll have a look. And jump the compressor

How'd you get 3lbs in there without the compressor running?

if your gauges are accurate, then 26inHg is showing you have a leak... in 1 hour you should be pegging the 29inHg mark on your gauges.
best way to check is with a micron gauge, but they are not easily attainable...

and it is simple to put in 3Lbs with no compressor engagement, you put in liquid in the high pressure hose... done.

I was using a fridge compressor to evacuate it - they only go to about 26 inHG. And it stayed there, so there is no leak, or at least a leak is not the problem.

The pressure is still there this morning but it's dropped a little, I guess because of the drop in temperature in the morning. Pressure is now 70PSI -that's enough to switch on the compressor isn't it?

I just realized I may have put a little too much ES-12 in - I put in just under 3 of the 6 oz cans, which they say is the equivalent of about 18oz a can. So that's 3lb 6oz and the 240D is only supposed to have 2lb 9 oz right? So that's quite a bit over.

However, that wouldn't stop the compressor switching on, especially since I had it switched on after the first can and it never came on. Time to jump the clutch...

Tell me how it remains liquid in the "evacuated" system??? I say it is NOT possible to put 3lbs in without condensing. If the OP has reads 75psi on both lines, the last 'empty' can had to have 75lbs psi when disconnected.

I'd suggest jumping the compressor clutch to +12 volts and see what your pressures do. If the low side goes into a vacuum add more. It could be the low side switch needs to be 'tickled' into action. Seen it before...

I don't recall the table, but I don't think 26 inHg is enough to boil the water out. If you do it again, you may get a bit better vacuum with the fridge compressor if you add a bit of DEC PAG 46 to the inlet before you start. I still purchased a dedicated pump, even though I have access to free fridge compressors.

Did you check for voltage at the clutch? It could be that your compressor is harder to start now, and the clutch gap is too wide. ESPECIALLY if you charged a liquid into the low side. If you did, don't force it to run. Turn it by hand a bunch of times. So many times that you think your fingers are going to come off.

It is very possible (and industry standard practice) to charge as a liquid. It must absorb heat to vaporize, and this heat will be easily given up when it condenses.

When you charge as a gas, you are absorbing heat in your can and that heat must be released into the system, thus it takes a long time, or a compressor.

Charging as a liquid does not need any help from the compressor at all. It's possible. I just did it. Most professionals do it every day.

I understand charging with liquid. I do it as well to speed the process.

However, I still say it is not possible to get a full charge, from cans, in the MB AC system without the comp running.

this is why it's important to weigh in a charge.
if you don't think you can put much freon in as a liquid, try it.
I have seen 10Lbs get dumped into a car system... the reciever frosted over, and the over pressure switch prevented the system from running when the guy tried to check the pressures.

a 30 Lb bottle makes it very easy to overcharge a system on the liquid side.

Then I did the impossible just a few weeks ago. The warmth from my hands was sufficient to empty the can into the system. And another one, and another one. That's enough over 2.2 lbs to account for the hoses.

if the car is in direct sunlight, it could be difficult, but if not, the system will indeed take over 3 lbs of liquid without engaging the compressor.

Well, this project which promised so much (parallel flow condenser and ES-12 performance) is really starting to suck.

Here's what we have so far.

Compressor is now running. I checked the relays - they both worked when 9v put across them. Checked all the fuses. Fine. PUt 12V across the clutch and it engaged. Hmmm. Doubled checked the fuses again in frustration - Fuse 14 was blown - How I didn't see that the last 3 times I checked the fuses, I don't know. Or maybe it just blew. I dunno.

Anyway, so now the compressor engages.

But, after 4 cans of ES-12 (6oz ea, supposed to be equivalent to 18oz R12) the low side still sucks a vacuum of 20 inHG and the high side is at 130PSI. FSM says it should be 30-45psi low, and about 250PSI high, given 85F ambient and 70 humidity.

SHHHEEEESH! What now? Put another can in? I really don't think there's a leak.

Low side too low and high side too low is classic low refrigerant isn't it?

Yes, VSTech, looks like I probably didn't get all the water out. At 26inHG water boils at 124F, vs 76F at 29inHG. Anyway, probably got most out of out, he says hopefully....

Your high side also suggests insufficient refrigerant.

If you get the low side to be correct, but the high side is spiking, you likely have air in the system. That will cause excessive high-side pressure, with no help for cooling.

Is it legal to reclaim this stuff and burn it in your grill?

Yeah, I've heard ES-12 is just propane, but when I looked at the MSDS it didn't make it clear. Alkanes or something.

So you think I should throw another can at it? High side is not spiking. It sits at 130PSI all the time the compressor is running.

I'm wondering how the lower pressures or characteristics of ES-12 effect the EX valve?

I don't know about the TXV with that stuff, but you need to have pressure in the low-side line to prevent the evaporator from freezing. Too little pressure and you will have excessive clutch cycling, which will wear it out.

Expansion valve stuck closed, or restriction in suction side of system?

You can't tell without the proper refrigerant level, but I would guess no. Consider the high-side reading.

I doubt the first, second and definately the third can was 'empty'.

So, You heard a sucking sound when you disconnected the can(s)
??? :rolleyes:

I do not doubt the accuracy of the triple-beam scale that I measured them on. I weighed the cans after disconnecting them on a Ohaus triple-beam scale, then again after discharging the "heel." 20 grams remained in each can. I'd call that "empty." How about you?

This does work.

I'd be willing to bet $100 that there was still a 'positive' pressure in those cans when you released them. Heck... make that $500. :eek:

I am 100% positive that there was pressure in the cans! That's not the issue at all.

There was no liquid left in the cans. That's the issue. All of the liquid went into the lines, and most of it went into the AC system.

Then the cans were NOT empty. There's no liquid in the system when it is static. If that's the "issue".

Still, I'd bet money that one cannot get 3lbs from cans into the MB system without the compressor running.

You are not understanding the process, and thus you don't believe. I'll take that bet for any amount of money that you want, but it will have to be enough to compensate me for my time. I'll even overcharge your system, if you want, without the compressor running. Let's make that bet a cool grand. I don't need the money, but I could find something to spend it on.

I tell you, this is industry standard practice. This is nothing new. Only DIYers who don't know better charge as a gas.

$1K it is then. And, if you don't need the money then why would you need to be compensated for your time?

How do we want to do this???

Either way, I'm confident it cannot be done. No need for a pissing a match here. But, I'll accept paypal. :D

Well, they've certainly got 'em whipped out and laid across the table don't they.......:D

Hmmm, steady lads!

Yes, WhiskyDan, there was some liquid left in the can when I disconnected it.

Back to the problem at hand - I posted at ackits.com and they suggested it is a restriction in the lines or a stuck TXV.

Do I get a cut on the $1k, for doing the intro work? Maybe I could buy some more refrig....

... carefull on taking that bet. you do lose some time and charge when you swap cans... with a 30Lb jug, I see easily charging or overcharging a system, with cans you will lose quite a bit in the charge hose, and what stays in the cans as you swap them out.
it can be done, but it will not be easy to do.

I'm not coming to TX. Next time you're in the St. Louis metro area, bring a car.

I want to be compensated for my time because this is just so useless. You are so sure this is impossible, yet it happens daily, and probably hundreds of times over.

And the goal can't be to put a vacuum in the cans, since this is impossible. The goal is to completely fill the system, isn't it? I can overfill it, just to be sure that it's possible to completely fill it.

Oh well, rest assured that this will never happen anyway, so your money is still safe. Why not go to a few AC shops and ask if they charge as a liquid? Ask them if they run the compressor during the liquid charge. When you find out how wrong you are, you don't owe me anything.

As I said, I left a mere 20 grams of refrigerant in each can as I swapped it out.

And now back to the studio.....

Update: Turns out it was the TXV - it was alll gooked up. Thanks for the pointers - I don't remember who suggested it, but they were right.

I posted on ACKITS.com about the issue, and when they heard I was using Enviro-safe then went nuts. Starting bashing me a bit and all. Anyway, I'm not convinced it is dangerous. Well, yes, it is dangerous if you have 2 cans of it open in your car (it is just butane and isobutane), and you light a match, but so is gas. Hmmm, I don't know. They use it in fridges in Europe, and in Canada they apparently use it a lot in cars. So who knows.

Anyway, thanks for the tips, looks like we've got this one solved.

So give us a report,how well is it working? Did you replace the exp valve or just clean it ? Curious minds want to know! I am planning on switching my 91 300d which was originally an R-12 system that had been converted to 134 before i got it over to ES-12a to see if i can get an improvement in the cooling,as it is now it cools but not great. Don

I definately replaced for the TXV (only $38), not worth the hassle to have to open and clean the lines and lose the refrigerant again. Read this article for some good AC tips. http://www.aircondition.com/wwwboard/alternative/current/7348.html. I believe it is him that says you should treat a stuck TXV like a compressor death. The dessicant in the drier blows out and clogs the TXV, so you have to clean the lines. I did it as well as I could without taking the compressor lines off. We'll see how long it lasts.

I emailed that guy and he said he has used ES12 on 40-60 cars with no problems. So I'm using it.

I didn't post the performance becuase I haven't been able to test it becuase I didn't have enough to properly charge the system. It is undercharged at the moment, I'm waiting for more refrig, then I'll test properly and let you know.

If you read that article, it says proper charging is nb with hydrocarbons and he gives how to do it.