AUTOMOTIVE R134a - LAND CRUISER 80 series

[syncview]

Hello everyone..

i'm new here and currently working on a car which is giving me a toughhhhh time.

the vehicle has three EVAPS, one on the front with a block type TXV, the fridge and rear unit has the traditional TXV with a 'remote bulb'

the system was originally a R12 system, but has now been converted to R134.

What has been changed:

front evaporator and txv
parallel flow condenser (from a serpentine condenser)
AC compressor SANDEN SD510
and of course R134a valves

All lines and EVAPS were flushed and old oil was removed completely.

currently the system is running with R134a, problem i'm facing is

if front is only used, cooling is perfect - no matter the vehicle or engine speed

if only rear in ON, cooling is again perfect, no matter the vehicle or engine speed

if both are ON together, front EVAP cooling goes south, >15 Celcius vent temps while the REAR UNIT works fine, <10 Celcius vent temps.

with both units ON, and vehicle running - the cooling gets better.
I've made sure that there is good airflow thru the condenser, i've made condensed foam duct between the radiator and condenser ensuring all air goes through the condenser, the mechanical fan has been set to partially engage at about 45 celcius and the condenser has two electrical high speed fans. so even at idle, there is a tornado going thru the condenser.


Fridge keeps working nicely all the time.

Pls see below table for further details, and pls also correct my SUPERHEAT and SUBCOOL calculations where needed :)

all temperatures are in CELCIUS
Pressures in PSI

EDIT: AMBIENT TEMP was 36C two inches away from condensor.

13742

[charlie patt]

Firstly what's ambient ? Firstly the suction pressure is two high either comp poor or undercharged .....on our three coil systems during idle there is solenoid valves that shut down one or two systems when running up the road they open up because engine revving more thus better suction also I have always found variable fan speed control on condensor fans on multi Evaps I would first disconnect fans and sea if they hit three hundred psi you are really after air of of four dc not ten the sol valves on our cruisers are inner wheel arch on toyota newer than 2001 thermo stat on fridge so only runs when ac to temp

[syncview]

AMBIENT temp was 36C about two inches away from condensor.

the systems were running during idle too, i had the thermostat set to coolest and blower to high, made sure that none of the systems tripped.


variable fan control? this is a 1993 Land Cruiser 80 series man.

If I disconnect both the electric fans, high side jumps by about 45-50 PSI - with only the mechanical fan running.

[syncview]

What do the subcool values tell you?

[mikeref]

Original condenser should have been replaced with the same configuration. The new parallel flow is highly efficient for a one on one ( evaporator / Condenser ) setup as it is designed for less refrigerant volume passing through.

3 Evaps with a high flow condenser doesn't leave any room for subcooling, let alone the refrigerant charge required to supply a full head of liquid on demand.

[syncview]

thanks a lot mate, i've performed further diagnosis including the unprofessional water test.. i'm going for the old style condensor

will update after i'm done

[syncview]

Original condenser should have been replaced with the same configuration. The new parallel flow is highly efficient for a one on one ( evaporator / Condenser ) setup as it is designed for less refrigerant volume passing through.

3 Evaps with a high flow condenser doesn't leave any room for subcooling, let alone the refrigerant charge required to supply a full head of liquid on demand.

Btw, do you think the serpentine condenser can cool down R134a nicely?

[charlie patt]

If head only jumps 45 psi on idle with fixed fan running I pressume u mean viscous fan that ain't enough pumping to me 89 to 93 models in uk have fan speed control in uk but we do have low ambient

[syncview]

Does it look like a bad or incompatible condenser?