AC

[MrAL]

Hello Everyone

I have a 1991 Chevy K5 blazer and it’s been about 10 years of me trying to fix the ac I’ve taken it to “experts” and they fix it but it only works for a few days. It’s been like this on and off for about 10 yrs and this weekend I summed up all the energy to do all of it, new ac condenser new ac compressor and it’s till won’t work is there some type of magic step I’m missing? Someone please help

 

[Wes Harden]

what is it not doing. Getting cold, blowing out the wrong vent or not blowing. I am guessing you've converted to r134a, was the new condenser a parallel flow style ?
No magic it's pretty straight forward, we'll get you sorted out.

Welcome to CK5

 

[MrAL]

It works for like 5 mins and then it stops. After I did everything today I had to stop because it sounded like the compressor was going to blow up

 

[Wes Harden]

do you have pressure readings for us ? It really helps narrow down whats going on. Also what kind of engine cooling fan are you using belt driven fan or electric ? maybe both ?

 

[tarussell]

It works for like 5 mins and then it stops. After I did everything today I had to stop because it sounded like the compressor was going to blow up

Also helps to be overly specific since the only info we have to go by is what you are giving - example: when you say that it stops; does that mean stops blowing cold or stops blowing air movement from the vents all together ?

 

[imiceman44]

Also helps to be overly specific since the only info we have to go by is what you are giving - example: when you say that it stops; does that mean stops blowing cold or stops blowing air movement from the vents all together ?

I am going to venture a guess.
He is converted to r134 and nothing else was changed from stock. it starts cooling until the condenser can't cool fast enough and now it's coming out warm.
I experienced that and I now know I need a new style parallel flow condenser.

 

[Wes Harden]

I am not sold on the r12 condenser being that inefficient to work with r134a.
In the 90s I converter 100s of Fords. All that was done new accumulator, and flush, add ester oil. All of them worked well enough for So Cal from the southern serrias to Bolder Nv.
That said op stated condenser has been replaced new. I don't believe any but a parrel flow is available any more.

 

[imiceman44]

I am not sold on the r12 condenser being that inefficient to work with r134a.
In the 90s I converter 100s of Fords. All that was done new accumulator, and flush, add ester oil. All of them worked well enough for So Cal from the southern serrias to Bolder Nv.
That said op stated condenser has been replaced new. I don't believe any but a parrel flow is available any more.

Well I converted 4 vehicles, and had the same thing happening.
I didn't change the orifice tube, would that be the problem?
I believe they have a different one for r134

I am still learning about automotive A/C

 

[Wes Harden]

Yes orcice tube is different. I change the tube almost any time I open a system. Already on the 3rd one in 01 burb. I tried the variable orfice tube fir "extreme" hit environments,and didn't like it.

 

[warrpath4x4]

Here is a pretty detailed post for converting from the R4 GM compressors to the better sanden compressors.

Sanden AC Conversion Guide

Sanden AC Conversion Guide

forum.73-87chevytrucks.com

 

[Wes Harden]

I understand you have new compressor, the converting to the Sanden style is highly recommended. The Harrison R4 is might be a great design, but it was poorly implemented.

I really don't like that R4 compressor much, so i might be bias

 

[Blue85]

It works for like 5 mins and then it stops. After I did everything today I had to stop because it sounded like the compressor was going to blow up

What kind of fan(s) is this? Low airflow will quickly cause it to stop condensing enough to get proper cooling. As you're saying, it can also build enough pressure to vent the refrigerant. The old quick test is to turn the garden hose on the condensor to see if the cooling performance returns. With A/C work, you shouldn't attempt anything but a small top-off without a proper gauge set on the system.

I am not sold on the r12 condenser being that inefficient to work with r134a.

All else being equal, the parallel flow "type" is more efficient than tube and fin, but in implementation almost nothing *is* equal. The parallel flow ones that are recommended aren't a big overall as the factory condensor, nor are they as fat, so the overall surface area is a lot lower. More or less the two effects equal out. The difference comes when you need to flush the system...

 

[MrAL]

Also helps to be overly specific since the only info we have to go by is what you are giving - example: when you say that it stops; does that mean stops blowing cold or stops blowing air movement from the vents all together ?

Replaced absolutely everything and for some reason we’re always getting clogged at the orafice tube, compressor wants to start to disintegrate. Compressor starts to over heat. Stops blowing cold air.

 

[imiceman44]

Replaced absolutely everything and for some reason we’re always getting clogged at the orafice tube, compressor wants to start to disintegrate. Compressor starts to over heat. Stops blowing cold air.

Did you make sure to flush out any remaining pieces of the system before you charged it?
If there was any hose or piece of equipment left, it should be flushed before you start vacuum

 

[gmbellew]

Replaced absolutely everything and for some reason we’re always getting clogged at the orafice tube, compressor wants to start to disintegrate. Compressor starts to over heat. Stops blowing cold air.

The system hasn't been properly flushed if this is happening. You need flush fluid and an air ompressor. Pull the system apart as much as possible and flush individual components to the extent possible to be sure everything has been flushed. In a burb with rear air that means removing (and sometimes replacing) the rear expansion valve.

 

[Wes Harden]

With blockage at orifice tube comes higher high side pressures, which will destroy something. If your lucky it will be a hose, if not a compressor.

To much oil can spike high side pressures. Always drain a new/rebuilt compressor, then refill with correct amount and type of per compressor mfg.
I do not care who assures me the compressor has the correct oil in it from the parts store, they are wrong.
Oil is cheap, compressors are not.