High Pressure Mystery

[chuckwp]

Trying to help out a fellow tech. in the shop. !996 VW Eurovan came into the shop with no cooling. Single A/C - front only. Technician replaced compressor, drier and espansion valve, flushed out condenser and evaporator, evacuated system and charged with correct amount of correct refrigerant. When first starting vehicle A/C works normally. However, after running a short while the high side jumps way up to 400 PSI!! Cooling fans working properly. Tried a know good pressure switch with no change. It seems like a restricted/clogged condenser but, the technician said the condenser flushed out well. Again: new compressor,drier, new expansion valve, proper charge amount, condenser fan working. Out of ideas. Input?

[Cusser]

Is that a serpentine type of condenser? Those are more likely amenable to reverse flushing than the parallel flow condensers, where solvent can bypass many passages. That's why parallel condensers are most often just replaced with new.

[chuckwp]

[quote="Cusser"]Is that a serpentine type of condenser? Those are more likely amenable to reverse flushing than the parallel flow condensers, where solvent can bypass many passages. That's why parallel condensers are most often just replaced with new.[/quote
I am not sure what type of condenser it is but, that could definitely be the problem! I will tell the tech. to check into it before he tears all his hair out! Thanks for the tip.

[chuckwp]

Update. Condenser has been replaced. Still excessive high pressure. (450 PSI) So, all major components have been replaced except evaporator. New compressor, condenser, drier,and expansion valve. Refrigerant charge level is correct and oil amount verified. It acts like a restriction in the high side or, an over charge but, that is not the case. At a loss. What are we missing?

[bohica2xo]

Condenser airflow issue.

Spray the condenser with water & watch the pressure drop like a rock.

Fan(s) not working / worn out & not reaching full speed etc.

[chuckwp]

Condenser airflow issue.

Spray the condenser with water & watch the pressure drop like a rock.

Fan(s) not working / worn out & not reaching full speed etc.

Fans working correctly. Does not make sense. Cannot find a restriction in the high side. No cold spots on the condenser. When/if we figure it out I will post the fix.

[bohica2xo]

400 psi is a condenser issue. HEAT is not being removed.

Spray the condenser with water & watch the high side pressure.

[Cusser]

400 psi is a condenser issue. HEAT is not being removed.

Spray the condenser with water & watch the high side pressure.

Have you tried this? bohica2xo knows his stuff, but cannot be there hands-on, so at least try this and report back to him.

[Dougflas]

After you spray the condenser with a hose and find that the high side drops like a rock, check to see if the fans are turning in the proper rotation. Also see if there is air flow going thru the condenser and radiator. Definitely appears to be a condenser air flow problem. This would not be the first time air went through the fans and bounced off the condenser instead of going thru it.

[Cusser]

After you spray the condenser with a hose and find that the high side drops like a rock, check to see if the fans are turning in the proper rotation. Also see if there is air flow going thru the condenser and radiator. Definitely appears to be a condenser air flow problem. This would not be the first time air went through the fans and bounced off the condenser instead of going thru it.

"You know what, Skipper? You're right too !!!" - Gilligan from Gilligan's Island