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Discussion Starter #1
My shop is completing a AC conversion from original R12 to 134a.
He also by passed the condenser switch. Could not locate part.
i did find OEM on Eeuro...
It ran cold for a brief drive maybe 15 minutes then blew warm.
They took it for a second drive the next day and still warm.
i live in Arizona , I’ve heard the AC doesn’t work well when really hot?
if it ran well initially ..is there a leak that big they couldn’t find that was obvious ? They did use dye ...
how many potential leak areas are there .
also, system has been inop for maybe 20 years , I’ve owned it 3, PO same. He never had it looked at due to temperate California climate..
Is this simple or complex..I’m prelexed ...
thanks!
 

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I don't know a lot about A/C systems, but I can tell you that the system in my 89 900S was converted to R134a back in the 90's (according to the sticker on the inner fender) and it is COLD. Really cold, and fast. So it is possible to convert and get more than satisfactory refrigeration.

In your case, I'd expect a leak somewhere, and maybe several somewheres. Every O-ring is probably shot, and the dryer is likely to be useless at this point. Also, make sure the radiator fan is coming on with the A/C.
 

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In the US there are procedures for refilling AC that must be followed (or $penalties$), and those procedures should eliminate leaks.

But, R134 runs at higher pressures than R12 and higher temps, so it's possible that a 20 year neglected system worked briefly and then failed... O-rings, compressor, etc.

I would be concerned about bypassing the low pressure switch... That is very poor practice and could result in serious damage to the system. The correct solution would be to find a substitute. A low pressure switch is a low pressure switch.. it is just threads and an electrical connection, not rocket science.
 

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It's a Flintstones-era system, anyone licensed should be able to diagnose it with gauges and a test light.
If the guys who converted it can't figure it out I wonder what they did to convert it.
As I recall, 5 switches (4 automatic) have to be closed (that's where the test light comes in), and you need a presurized system the compressor can pump (use gauges).
I've converted literally hundreds of SAABs and never bypassed any switches.
All the O-rings will be fine unless someone fiddled with them. What did the UV dye show?

I'm not used to the term 'condenser switch,' others are assuming it's the low-pressure switch. Where is it?
 

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Discussion Starter #5
It's a Flintstones-era system, anyone licensed should be able to diagnose it with gauges and a test light.
If the guys who converted it can't figure it out I wonder what they did to convert it.
As I recall, 5 switches (4 automatic) have to be closed (that's where the test light comes in), and you need a presurized system the compressor can pump (use gauges).
I've converted literally hundreds of SAABs and never bypassed any switches.
All the O-rings will be fine unless someone fiddled with them. What did the UV dye show?

I'm not used to the term 'condenser switch,' others are assuming it's the low-pressure switch. Where is it?
Hey Jim- they have not issued me a dye test result . The switch he mentioned is attached to the compressor . He did not replace the dryer . The ‘conversion ‘ kit just contained the fittings for the new freon I’m assuming go on the old dryer .. forgive me if that’s not accurate I don’t know AC parts ..curious why it did work originally then stopped ..
Any heat theory’s you have heard of , like when it’s to hot out the system Won’t work ?? I’m in AZ.
 

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That switch, as pictured, doesn't fit a 900. I'm sure it's just a generic picture of a generic switch. Certainly don't buy one of those for $84.
I ask because there really is no 'condenser switch.' The low-pressure switch is on the receiver/dryer.
If anything, that looks like one of the coolant switches (one on radiator, one in upper hose), but the connectors are wrong. Maybe they bypassed a high-temperature cutoff switch on the top hose?
None of this story makes much sense. Is it charged? What are pressures? Does it work electrically or is some switch broken?
 

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I misread... There is also a switch on the condenser, that is not the low pressure switch. Point stands... No reason to do that.
 

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That's a high-pressure switch. It operates on the high side of the compressor on some cars.
It prevents excess pressure from a clogged expansion valve or receiver/drier.
A clogged system with the high pressure switch bypassed can produce some dangerously high pressures, Wear safety glasses when working on it.
 
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