Automotive Air Conditioning Information Forum

Hello,

Not to hijack the discussion here but how is it that General Motors & other air conditioning systems can be dependably and safely made to work in cold winter time temperatures when set to defrost?

This setting cycles the compressor to chill and dry the air prior to blowing across the inside of the windshield glass with apparently good functionality in cold temperatures.

Rick

That should be a separate thread

I'm guessing, but there could be a restriction of some sort at the union where the two tubes join in your photo. For instance, desiccant beads from a failed R/D tend to hang up in places like that, as well as at the TXV.

Maybe one of the shops shoved an orifice tube in the liquid line? There is an old style tube-o threaded connection a few inches upstream of where the frost happens

Interesting thought, DetroitAC. I suppose if an OT fit in there, it's possible.

DetroitAC wrote: ↑Mon Jul 05, 2021 3:23 pm Maybe one of the shops shoved an orifice tube in the liquid line? There is an old style tube-o threaded connection a few inches upstream of where the frost happens

I did wonder myself if there could be an orifice tube in at this location (that might be partially blocked). I don't seem to be able to find any diagrams on the cars a/c system, but there seems to be only an orifice tube available to purchase for a 2008 Volvo C30. I didn't expect that.

Paul, diagrams of this car that I can find are pretty useless, but it appears to me to be an orifice tube system.

I think what you see as a receiver is in fact an accumulator? confirm? are the pipes going in and out of this "can" roughly 19mm diameter ==>Accumulator, or are they 10mm or less ==> Receiver

Also the pipes would go: Condenser -->Receiver-->TXV
OR
Evaporator -->Accumulator -->Compressor

Please confirm what you have

If I assume you have the correct amount refrigerant charged, and you are getting ice from right at the orifice tube, then you have debris plugging up your orifice tube. Recover charge, put in a new orifice tube, or backflush the existing if you must, evacuate, recharge to underhood sticker amount by weight.

Just an off-topic comment, we don't really need to know the static pressure, it only tells you in fact have refrigerant in there and not kerosene or olive oil or whatever. Static pressure is no help at all in determining how much refrigerant you have

DetroitAC wrote: ↑Tue Jul 06, 2021 8:16 am Paul, diagrams of this car that I can find are pretty useless, but it appears to me to be an orifice tube system.

I think what you see as a receiver is in fact an accumulator? confirm? are the pipes going in and out of this "can" roughly 19mm diameter ==>Accumulator, or are they 10mm or less ==> Receiver

Also the pipes would go: Condenser -->Receiver-->TXV
OR
Evaporator -->Accumulator -->Compressor

Please confirm what you have

If I assume you have the correct amount refrigerant charged, and you are getting ice from right at the orifice tube, then you have debris plugging up your orifice tube. Recover charge, put in a new orifice tube, or backflush the existing if you must, evacuate, recharge to underhood sticker amount by weight.

Just an off-topic comment, we don't really need to know the static pressure, it only tells you in fact have refrigerant in there and not kerosene or olive oil or whatever. Static pressure is no help at all in determining how much refrigerant you have

Thank you very much for trying to help. Weather here is poor, so I've not been able to investigate further. I think you would be correct about the accumulator, with it being more suitable for a orifice tube type system, and there are 19mm diameter pipes going in and out of the can. Also, now that I look, where the ice forms, the tube appears to be nipped in, in 3 places at the same point around its diameter, perhaps suggesting further that it is indeed the location for an orifice tube.

My limited understanding of a/c would say the system high pressure runs, Compressor >Condenser >accumulator > TXV (which as you say seems to be an orifice tube type).

OK, apologies for the unnecessary information regarding the static pressure. I read that it was a way of checking correct charge volume, but that is perhaps one of many things I should have ignored. I have read that too little refrigerant could cause ice to form after the orifice tube, is that correct?

When the rain stops and I get a moment, I will do exactly as you say. Sincerely, thank you for taking the time.

" I read that it was a way of checking correct charge volume"
Not really.

If you have an accumulator and thus an orifice tube, the flow is like this, as Detroit diagrammed:
comp-->condenser-->OT-->evap-->accum--> back to comp

OT and TXV are very different expansion devices

I was thinking all along that this was a TXV system. But it appears to be a CCOT system. If so, it's time to recover the charge, pull the OT, and examine it. If it's full of black gunk and particulates, then we have more problems to address other than replacing just the OT.