2/93 A/C Mystery - Need Ideas and Help

[e9999]

LOL. This seems to be where we have been ending up. How about process of illimination? Let's see, if we can rule out the thermister, amp, switched, relays, etc... Then it would have to be either in the actual lines, or an actual part.

Now, we know there is no blockage because if there were, the high pressure would rise or be higher than 230 or so. So we can rule out a blockage.

The pressure on the Lo side is 21-30 and the pressure on the Hi side is 185-215, so everything looks great, but we are not (cool).

The reciever is showing bubbles while the compressor is enguaged. At least, it looks like bubbles because it looks all foamy. Then Clear when the compressor stops.

Think real hard....If all is well, and we have bypassed the switches, amp and sensors by adding direct power to the compressor clutch, and the pressure is in range, and the system will not cool quickly or really ever get below 50 degres, what could it be?

I thought that there should be no bbls when the compressor has been going on for a bit? (IIRC - no FSM on hand)

 

[Gieser]

I thought that there should be no bbls when the compressor has been going on for a bit? (IIRC - no FSM on hand)

What is the glass supposed to look like. I understood it was supposed to be clear when the clutch is not enguaged and bubbly when it is engaged. When I say bubbly, it looks foamy and can clearly see it passing through.

 

[-Spike-]

The pressure on the Lo side is 21-30 and the pressure on the Hi side is 185-215, so everything looks great, but we are not (cool).

The reciever is showing bubbles while the compressor is enguaged. At least, it looks like bubbles because it looks all foamy. Then Clear when the compressor stops.

I'm sorry for not being able to follow all the different A/C threads and make perfect sense of them in my head. I don't remember seeing you post the pressures, or they didn't catch my eye before, or someone (Tools?) said they looked fine.

The pressure looks low to me, like undercharged. I am NOT an A/C expert. I filled mine by volume- 30 ounces and 6 ounces of oil. I put slightly less oil in than FSM recommends because I figured there was still some in the compressor that I couldn't get out. My pressures are way higher than yours, and way higher than the ~36 low and ~220 high that the FSM recommends, which I attributed to the inferno that I live in. Did you fill by pressure or volume?

-Spike

 

[Tools R Us]

By hot wiring, "cheating" the compressor on you eliminate the electronic controls and run purely on manual, showing the true maximum potential of the system. The expansion valve is new and performs well in gauge readings, blockage would show in gauge readings. Gauge readings are good, maybe a little low and vent temps, ambient split is low.

That leaves only a couple of things that I can think of, you can try adding more R134, go slow, add maybe enough to bring the hi side up 10 PSI, allow the system to stabilize and check vent temp, if it goes down try adding a little more. R134 can be picky about charge some systems like a hair more than others, it's also easy to over do it.

The other thing is freon contamination, incompatible oil mix, dye, seal conditioners, etc. A lot of the off the shelf cans have this type of additives and may not be compatible with the trace oils, etc., left over from the original charge or added in the new charge. Was the system charged with new virgin R134 or reclaimed? Did it have any additives?

We had this type of problem with brother Rob's truck last year and wound up flushing and recharging with virgin freon to fix it.

You may find something helpful by searching this forum. http://acsource.net/acforum/

 

[Tools R Us]

I'm sorry for not being able to follow all the different A/C threads and make perfect sense of them in my head. I don't remember seeing you post the pressures, or they didn't catch my eye before, or someone (Tools?) said they looked fine.

The pressure looks low to me, like undercharged. I am NOT an A/C expert. I filled mine by volume- 30 ounces and 6 ounces of oil. I put slightly less oil in than FSM recommends because I figured there was still some in the compressor that I couldn't get out. My pressures are way higher than yours, and way higher than the ~36 low and ~220 high that the FSM recommends, which I attributed to the inferno that I live in. Did you fill by pressure or volume?

-Spike

R134 is more temp active than R12, his readings are at 80F lower than we are used to seeing. I agree that they look slightly low even for that temp, but be careful adding more, go slow it's easy to overcharge R134.

 

[Gieser]

Did you fill by pressure or volume?

I believed they filled by volume to around 28. When they had it hooked up at the shop in the heat of the day, the Lo was reading about 28 and the high was at like 220, last night in the cooler air the Lo was 21 and the Hi was 180.

 

[Gieser]

you can try adding more R134, go slow, add maybe enough to bring the hi side up 10 PSI, allow the system to stabilize and check vent temp, if it goes down try adding a little more.

Could just a little lack of R134 cause a 10 degree diference in vent temp?

The other thing is freon contamination, incompatible oil mix, dye, seal conditioners, etc. A lot of the off the shelf cans have this type of additives and may not be compatible with the trace oils, etc., left over from the original charge or added in the new charge. Was the system charged with new virgin R134 or reclaimed? Did it have any additives?

The shop charged it the first time with virgin. They have charged it every time and have not added anything to it. I will check to see if the last charge was virgin or not.

 

[Gieser]

I just confirmed the charge was new with no additives.

 

[medtro]

I believed they filled by volume to around 28. When they had it hooked up at the shop in the heat of the day, the Lo was reading about 28 and the high was at like 220, last night in the cooler air the Lo was 21 and the Hi was 180.

Are these readings taken at around 850 RPM? The NORMAL readings shown in the FSM are for engine running at 1500 RPM.

 

[Gieser]

Are these readings taken at around 850 RPM? The NORMAL readings shown in the FSM are for engine running at 1500 RPM.

I forgot about the 1500 RPM reading and they may have not read it from there, either. Those reading were from 850 RPM. Hmmmmm...the lower the RPM, the higher the readings, so the higher the RPM, the lower the readings. Let me start her up and let her run for a few minutes and take the readings at 1500. Be back in a few.

 

[Gieser]

Results Tested at 1500 RPM at normal operating temp, etc

Clutch enguaged:
Lo was less than 10
Hi was at 160-170

 

[FJ809496TLC]

Read post #72. You're undercharged.

 

[-Spike-]

I guess that's the most probable reason, you're low on refrigerant.
Go kick your A/C guy in the shin for me.

-Spike

 

[-Spike-]

R134 was used
Parts were pre oiled
The lines were perged
expansion was new OEM
High Pressure is 380
Low pressure is normal around 30

This is post #4 in this thread. Something change since then? Leak?

-Spike

 

[FJ809496TLC]

I guess that's the most probable reason, you're low on refrigerant.
Go kick your A/C guy in the shin for me.

-Spike

Make that 2X.

 

[Gieser]

Quote:
Originally Posted by Gieser
R134 was used
Parts were pre oiled
The lines were perged
expansion was new OEM
High Pressure is 380
Low pressure is normal around 30


This is post #4 in this thread. Something change since then? Leak?

-Spike

The only thing that changed after the high reading was a replacement of the fan clutch which brought down the high side.

 

[Gieser]

Read post #72. You're undercharged.

It looks that way. Do I need to actually charge it while it is at 1500rpm?

 

[Gieser]

I guess that's the most probable reason, you're low on refrigerant.
Go kick your A/C guy in the shin for me.

If he charged it at the normal 850 RPMs, then would it look full but not actually be full since the FSM says at 1500 rpm?

I am going add it VERY LITTLE AT A TIME but do I need to actually have it running at 1500 rpm?

If this is what it is (which by the way, this was not the main problem before the fan clutch...that made a lot of difference in the readings and air flow accorss the condenser) I will kick him for everyone on this thread

 

[FJ809496TLC]

It looks that way. Do I need to actually charge it while it is at 1500rpm?

It will charge faster but you don't have to as long as you put the right amount of freon. Do you still remember how much you put in?

 

[Gieser]

It will charge faster but you don't have to as long as you put the right amount of freon.

I am sitting here reading the FSM and it says to charge it at normal idle, but test it at 1500 RPM, so I guess I sould charge it a little higher on the low idle small amounts at a time.