AC mystery
04-18-20, 11:39 AM
#1
7th Gear
Thread Starter
AC mystery
Hi everyone.
This is my first post on this forum.
I've purchased 2005 SC430 with 78,000 miles month and a half ago.
PO had it parked for almost a year, not using it.
She claims AC worked great when parked.
It was 60 F on the day of purchase.
Compressor kicks in and works all the time but blows air same like outside.
Being 15 years old, I thought it was probably low on refrigerant.
Lady owned the car for last 10 years and AC always worked fine, no service done.
My friend evacuated the system and recharged it to proper amount.
System had 1.2 lb in it before being vacuumed and he put back 1.4 lb.
Nothing changed, compressor kicks in and continuously work but no cold air.
My friend starts checking different things and he vacuums and recharges the system again.
He was testing pressure switch and checking connections. He was also tapping the switch.
Suddenly AC tarts blowing ice cold air like nothing happened.
Everything worked great for a week.
Again, same situation. Compressor kicks in and works all the time but no cold air.
After reading online for hours, it seems that AC pressure switch has nothing to do with this since its only duty is to shuts compressor down if pressure is too high or too low.
My compressor kicks in every time and stays on.
Why AC started working fine and worked great for a week is mystery.
Next suspect was Expansion valve.
He replaced it and air was now blowing cool air inside but not cold like before.
Low pressure pipe under the hood got cold immediately after AC was turned on but became warm and stayed that way all the time.
It was improvement but far from good.
Same day he also replaced AC pressure switch with used one that according to seller came from good AC working car. That made no difference.
3 days later I've stopped by local AC shop and tech told me that both low and high pressure side are reading too high.
It was 86 F outside and my pressure reading were 50psi on low side and 210.
Tech told me low side should be 30-40 psi and high should be 150-200.
He told me that means there is no restrictions in the system and nothing is clogged. Hes opinion was that AC was low on refrigerant and recommended double checking that AC is properly charged and if it is properly charged, his next suspect would be compressor. Compressor is easy to replace but everything I've read says that compressors fail gradually and never work on and off. It is confusing that it started working and worked great for a week.
I didn't want to bother my friend that day and I just took a can of refrigerant to try to add myself. Gauge that came with can was showing high pressure and wouldn't take any more. I did discharge little bit of gas to see if that would lower the pressure but nothing happened.
I left it alone since the last week.
I was checking online again and it's confusing about proper pressures.
Found several charts that are showing pressures of 50psi and 210psi normal at the outside temp of 85F.
But at the same time I've found several statements saying low side should be 30-40psi always.
My friend will be working again on my car next weekend. I've purchased new condenser and new compressor, both Denso and we are planning to replace condenser first and try it. If nothing we would then replace the compressor and see if there is any results.
I would really appreciate your input in order to solve this problem.
Thank you
This is my first post on this forum.
I've purchased 2005 SC430 with 78,000 miles month and a half ago.
PO had it parked for almost a year, not using it.
She claims AC worked great when parked.
It was 60 F on the day of purchase.
Compressor kicks in and works all the time but blows air same like outside.
Being 15 years old, I thought it was probably low on refrigerant.
Lady owned the car for last 10 years and AC always worked fine, no service done.
My friend evacuated the system and recharged it to proper amount.
System had 1.2 lb in it before being vacuumed and he put back 1.4 lb.
Nothing changed, compressor kicks in and continuously work but no cold air.
My friend starts checking different things and he vacuums and recharges the system again.
He was testing pressure switch and checking connections. He was also tapping the switch.
Suddenly AC tarts blowing ice cold air like nothing happened.
Everything worked great for a week.
Again, same situation. Compressor kicks in and works all the time but no cold air.
After reading online for hours, it seems that AC pressure switch has nothing to do with this since its only duty is to shuts compressor down if pressure is too high or too low.
My compressor kicks in every time and stays on.
Why AC started working fine and worked great for a week is mystery.
Next suspect was Expansion valve.
He replaced it and air was now blowing cool air inside but not cold like before.
Low pressure pipe under the hood got cold immediately after AC was turned on but became warm and stayed that way all the time.
It was improvement but far from good.
Same day he also replaced AC pressure switch with used one that according to seller came from good AC working car. That made no difference.
3 days later I've stopped by local AC shop and tech told me that both low and high pressure side are reading too high.
It was 86 F outside and my pressure reading were 50psi on low side and 210.
Tech told me low side should be 30-40 psi and high should be 150-200.
He told me that means there is no restrictions in the system and nothing is clogged. Hes opinion was that AC was low on refrigerant and recommended double checking that AC is properly charged and if it is properly charged, his next suspect would be compressor. Compressor is easy to replace but everything I've read says that compressors fail gradually and never work on and off. It is confusing that it started working and worked great for a week.
I didn't want to bother my friend that day and I just took a can of refrigerant to try to add myself. Gauge that came with can was showing high pressure and wouldn't take any more. I did discharge little bit of gas to see if that would lower the pressure but nothing happened.
I left it alone since the last week.
I was checking online again and it's confusing about proper pressures.
Found several charts that are showing pressures of 50psi and 210psi normal at the outside temp of 85F.
But at the same time I've found several statements saying low side should be 30-40psi always.
My friend will be working again on my car next weekend. I've purchased new condenser and new compressor, both Denso and we are planning to replace condenser first and try it. If nothing we would then replace the compressor and see if there is any results.
I would really appreciate your input in order to solve this problem.
Thank you
Last edited by deejay2005; 04-18-20 at 01:01 PM. Reason: Adding more info
04-18-20, 01:57 PM
#2
Lead Lap
I don't know much about a/c systems but the fact that it started working abruptly and then later stopped sounds like there is a bad or stuck switch somewhere.
04-19-20, 08:47 AM
#4
I had an issue similar to this a few years back & it was the compressor. It didn't go out gradually, it just wasn't working one day. You did say that flicking the switch made it come on once, which switch was that, the on/off button on the dash ? Could it be possible that you have a shortage, in the button or possibly the climate control unit ??
04-19-20, 09:03 AM
#5
7th Gear
Thread Starter
When my friend was playing and tapping AC pressure switch , AC started blowing cold. We did replaced it with used one just to try but no difference. Everything points it's not pressure switch, compressor wouldn't turn on with faulty pressure switch. My compressor and fans turn on every time when AC is turned on. Also we never had AC light blinking, indicating a problem like many other owners experienced.
The following users liked this post:
deejay2005 (04-19-20)
04-21-20, 11:53 AM
#7
Pole Position
Read this post. Especially post #5 and Post #16. It might help you diagnose what the problem is
https://www.clublexus.com/forums/sc4...sue-sc430.html
https://www.clublexus.com/forums/sc4...sue-sc430.html
The following 2 users liked this post by DshngDaryl:
deejay2005 (04-22-20),
Ozrkcowboy (04-21-20)
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04-22-20, 07:45 AM
#8
7th Gear
Thread Starter
Checked for AC codes and display was showing 00.
AC light never blinked, indicating problem.
Everything appears to be working fine but no cold air and low pressure line is not cold.
Anyone else with idea?
AC light never blinked, indicating problem.
Everything appears to be working fine but no cold air and low pressure line is not cold.
Anyone else with idea?
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