Mystery A/C High Pressure

louiss3000 · Post by **louiss3000** » 03 Oct 2020, 11:33

Hello all,
I have this A/C high pressure issue that basically has me stumped. 2003 V70 2.4t. A/C worked fine. Recently had an issue where A/C just stopped, clutch disengaged. After a bit, the clutch would re-engage but cycle. Low pressure I guessed, maybe a leak, it did blow off the high side hose once. Put the gauges on, static pressure was 145, seemed odd but OK. Started the car, high side went to almost 400, and clutch disengaged. High mileage car, so I suspected that the filter/drier may be clogged, although I did replace it after the hose incident, recovered the refrigerant, changed the drier and the expansion valve, charged to 1kg per the sticker, all seemed well. Later I hear this noise like a vibrating hose of loose bracket of some type, the A/C quits, put the gauges on again, high side at 375. Thinking clogged condenser, but the pressure sensor and the high side port are after the condenser. So I changed the expansion valve again, same result. Is it possible to have a clogged evaporator? There's only a hard line between the drier and the TXV, so a collapsed hose liner would be ruled out.

Any Ideas are appreciated.Thanks in advance...

Post by **jimmy57** » 03 Oct 2020, 12:23

Is the cooling fan kicking up to a really high (loud) speed?
Is air path throiugh the condenser/rad/intercooler clear?
Static pressure is related to temp. 145 psi would be 107 degrees or thereabouts and that is possible when engine has been run and radiator is hot and engine heat is escaping. Static pressure is not affected by overcharge or under charge until you get way off normal amount either way so it is not useful as correct charge indicator.

louiss3000 · Post by **louiss3000** » 03 Oct 2020, 12:41

Fan is on high, I can hear and feel it blowing, water hosing the condenser doesn't really help. Condenser is clear and clean. The static pressures were with hot engine / rad, etc. I listed the static because I was expecting something lower, as I was assuming low or absent charge. Wasn't thinking high pressure cut-oui. I have tried three TXVs now, same result. As I mentioned, this is a new drier, but had same issues with the old one. I could manually blow through the old drier. Next try is to disconnect outlet of drier and that joint just in front of the alternator pulley and blow some nitrogen through. Then remove TXV and blow forward then reverse. I do mostly residential A/C, and many older cars, but have never seen a restricted evaporator. Ideas?

Post by **jimmy57** » 03 Oct 2020, 20:03

I have never seen a restricted evaporator on any TXV system as TXV is the choke point. I have seen orifice tubes let stuff pass when the screens break. I mentioned the static as I see 140-150 often when I run a car for a while and have gauges on it I have kept connected. It sure seems like something plugged high side and everything after is the result. Have you looked at every inch of the liquid line from condenser to TXV? A dent on that line could do it. If it is still charged run engine and have some one turn on a/c while you feel that line for a frost point where a restriction exists that makes that spot act like an expansion valve.