Air Conditioner lines freeze - why ??

[calflan]

After the air conditoner has been ON for 20 minutes or more, the lines from the accumulator freeze up and the airflow from the ducts slows nearly to a nothing at all. No cold air either. Recently had the system vacuumed and reserviced with freon. Same condition after servicing.
Why would the lines be freezing ?
Is the expansion valve able to be changed or is there a assembly that contains it ?

Thanks.

[Hooligan]

I'd take it back where you had it serviced and tell them what the problem is. They are the experts.

[CREWZIN]

The most probable cause for the system to freeze up is the High Pressure switch located on the accumulator next to the firewall. I had the same thing happen.

[outfit]

I have an 06 PT Touring and the same thing happen to me, i had a thread about it a couple of weeks ago, I had some other problems though, compressor to condensor hose had a leak, rad fan was out, well it was almost out, the fan could be stopped with your hand.. After all that was done I forgot to replace the part that Crewzin told me... I would take their advise... they got skills

[calflan]

Thank you for the responses.
I will go after the switch first. After revieiwng some of the schematics, etc., I wondered if the switch muight be the cause, but not exactly sure why.
When the HP switch cuts out, any cold flow in the lines is locked there and freezes ?

Thanks again. This switch is 'probably' the least expensive as well. I was going to start at the condensor - which like all components - is not cheap for a shotgun troubleshoot.

[CREWZIN]

Originally Posted by calflan

When the HP switch cuts out, any cold flow in the lines is locked there and freezes ?

From a search: A high pressure switch disconnects power to the compressor clutch if the pressure gets too high. This can happen if you have electric fans and they stop working or if the condenser is clogged with bugs or anything else you may have picked up while driving, such as a piece of newspaper or a plastic bag. Of course if any of these have happened you will have a high engine temperature too. You can bypass the high pressure switch just to see if it is faulty. If it is, then the clutch will engage when you turn the a/c on and you need to replace that switch. DO NOT try to fun the system without a working high pressure switch as this can lead to very expensive problems such as blown hoses and compressors.

[outfit]

I found the High Pressure Cut-Out Switch at O'reillys part # 20050 for $13.49... but if you find that you need expensive items, such as with chrysler dealer items, try rockauto.com very good deals

[slartyblarfast]

Most likely your problem is the clutch cycling switch which is on the accumulator. It's probably stuck closed which is allowing it to freeze up.

[CREWZIN]

Originally Posted by slartyblarfast

Most likely your problem is the clutch cycling switch which is on the accumulator. It's probably stuck closed which is allowing it to freeze up.

I'm pretty sure that your "Clutch Cycling Switch" is the same as my "High Pressure Switch".

[calflan]

Thanks guys. In changing the HP switch, I assume it is under pressure ? I will have to bleed off system pressure before replacing and reservice system ?