TXdragon4runner
New member
Hey fellow 4runners - greetings from North Texas - (Dallas Ft Worth).
Appreciate your help catching where I may have missed the obvious needed repair. Followed many of the recommendation here on T4R.org as well as Timmy The Toolman videos (love those 3rd gen videos of his).
Vehicle:
1999 Toyota 4Runner, Base model 2.7L, 5 speed, 2 wheel drive, MANUAL a/c (has the AC Amplifier not a "second relay" as many folks seem to think).
runner has 245,000 miles - dusty, hot texas miles - use it to run out to west texas ranch and back to DFW area all the time.
2nd owner since 130,000 miles This is one of 6 (yes 6) 3rd gen 4runners I have. My kids drive them as well.
I have used my "trusty" Harbor Freight Manifold gauge set a number of times to check, evac, draw vacumn, and recharge a/c on my other runners. ... point is, i know enough to be successful but certainly not an expert on A/C systems.
Problem for 1999 4runner:
A/C wasn't cooling below 66.2 degrees.
I didn't specifically check ac compressor clutch engaging or not, just assumed it was ok as system would cool down to 66.2 degrees but no further. just Assumed. yeah I know. Guessed i had a R134a issue. Simple recharge and done - right?
But no....never that simple is it.....
today 6/26/21, i am guessing the root cause is within the a/c pressure switch circuit - or could it be too much PAG oil in system? guessing here ...
The Symptom:
Compressor clutch will not remain "engaged".
The compressor clutch will engage for 5-10 seconds, then cut out and will not re-engage - unless vehicle is shut off and restarted.
The twist: This is AFTER I replaced a/c components (using Denso) as called out below.
BACKGROUND / Process Steps I followed:
For the 1999 -
Decided i would replace the A/C components due to amount of use and simple fact we'll keep it another 245,000 miles.
Bought new parts via Amazon - all Denso products - as noted here - Denso units actually shipped direct from Denso warehouse in SoCalif...
- Condenser - Denso
- Receiver - Denso
- Compressor - Denso
- Evaporator Core - Denso
- Expansion Valve - Denso
- Thermister and clip (Toyota OEM)
- Pressure Cut Off Switch - (Toyota OEM)
- O ring set (4 seasons green set) just in case denso didn't send enough
- misc parts all OEM from Toyota i.e. packing for Evap Case etc.
Replaced all parts easily enough. Helps to remove the airbox.
Evap case was a slight annoyance but all together pretty easy process to replace components.
Got everything in. Triple checked connections, torque values etc. Looked good.
Charging System: aka - The place of broken dreams....
1/ Pulled vacumn for 45 minutes, remove line from pump
2/ Checked for leaks by waiting 1.5 hours - no issues, vac remained at 30 psi
3/ connected one can of r134a to gauge set
4/ puncture can, bleed the "yellow' line to ensure no air in line
5/ started engine; ac on, max cool, recirculate mode, all windows down
6/ boosted RPM to 1,500-1,600
7/ opened low side manifold knob expecting good things but no....
8/ low side pressure started reading at 70 psi
9/ after a few minutes low side pressure started building, first 70 psi, then 80....then 90.... closing in on 100 psi .... so I closed off manifold (low side valve), killed engine.
** I didn't catch the HIGH side psi reading as I worried about low side
** Ambient weather in DFW area on 25 June was about 40% humidity, 98 degrees F, (god I miss North County San Diego weather....)
I repeated my steps (1-9) 3 more times and got same results each time. ....didn't see cycling, the RPM's on engine would drop a bit on occasion but not what I see on my other runners when ac is cycling, not same load/rpm drop.
I put a high visibility mark on the ac clutch to check if it was spinning, again it would spin once then no more. when it spin low pressure psi reading are what you would expect/see when charging a system with r134a.....
I bypassed the new pressure switch by jumping the switch connector (using paper clip) - same patten, clutch engages, for 5-10 seconds, can see low pressure gauge drop down to say 20 psi, then clutch cuts off and will not reengage unless engine shut off then back on. i.e. one clutch engagement per engine on/off cycle.
At times, I could hear engine RPM drop slightly....but not what i see with my other runners when ac cycles/clutch engages and no movement on gauges (low side dropping to 20-25-30 psi for a normal charging cycle)
No idea why a new dense compressor clutch would kick on 1 time for 5-10 seconds, systems function as it should for those precious seconds then clutch doesn't engage again without resetting. Guessing issue on electrical circuit...
Could it be:
1/ AC amplifier switch failure?
2/ Too much PAG oil? Son thinks we may have put too much into system:
New Compressor had 3.9 oz - we drained new compressor then put back that amount - or did we add more - we didn't document ...
3/ per denso recommendations we added PAG : to condensor 1.4 oz, receiver, 0.70 oz, evap core 1.4 oz - trying to find an answer we are speculating that we may have added these amounts to the compressor in addition to the original 3.9 oz....essentially adding 2x the condenser, receiver and evap core volumes.
4/used Denso OD-Oil 8 (PAG 46)
Lord knows we missed something....Appreciate the help on this.
Appreciate your help catching where I may have missed the obvious needed repair. Followed many of the recommendation here on T4R.org as well as Timmy The Toolman videos (love those 3rd gen videos of his).
Vehicle:
1999 Toyota 4Runner, Base model 2.7L, 5 speed, 2 wheel drive, MANUAL a/c (has the AC Amplifier not a "second relay" as many folks seem to think).
runner has 245,000 miles - dusty, hot texas miles - use it to run out to west texas ranch and back to DFW area all the time.
2nd owner since 130,000 miles This is one of 6 (yes 6) 3rd gen 4runners I have. My kids drive them as well.
I have used my "trusty" Harbor Freight Manifold gauge set a number of times to check, evac, draw vacumn, and recharge a/c on my other runners. ... point is, i know enough to be successful but certainly not an expert on A/C systems.
Problem for 1999 4runner:
A/C wasn't cooling below 66.2 degrees.
I didn't specifically check ac compressor clutch engaging or not, just assumed it was ok as system would cool down to 66.2 degrees but no further. just Assumed. yeah I know. Guessed i had a R134a issue. Simple recharge and done - right?
But no....never that simple is it.....
today 6/26/21, i am guessing the root cause is within the a/c pressure switch circuit - or could it be too much PAG oil in system? guessing here ...
The Symptom:
Compressor clutch will not remain "engaged".
The compressor clutch will engage for 5-10 seconds, then cut out and will not re-engage - unless vehicle is shut off and restarted.
The twist: This is AFTER I replaced a/c components (using Denso) as called out below.
BACKGROUND / Process Steps I followed:
For the 1999 -
Decided i would replace the A/C components due to amount of use and simple fact we'll keep it another 245,000 miles.
Bought new parts via Amazon - all Denso products - as noted here - Denso units actually shipped direct from Denso warehouse in SoCalif...
- Condenser - Denso
- Receiver - Denso
- Compressor - Denso
- Evaporator Core - Denso
- Expansion Valve - Denso
- Thermister and clip (Toyota OEM)
- Pressure Cut Off Switch - (Toyota OEM)
- O ring set (4 seasons green set) just in case denso didn't send enough
- misc parts all OEM from Toyota i.e. packing for Evap Case etc.
Replaced all parts easily enough. Helps to remove the airbox.
Evap case was a slight annoyance but all together pretty easy process to replace components.
Got everything in. Triple checked connections, torque values etc. Looked good.
Charging System: aka - The place of broken dreams....
1/ Pulled vacumn for 45 minutes, remove line from pump
2/ Checked for leaks by waiting 1.5 hours - no issues, vac remained at 30 psi
3/ connected one can of r134a to gauge set
4/ puncture can, bleed the "yellow' line to ensure no air in line
5/ started engine; ac on, max cool, recirculate mode, all windows down
6/ boosted RPM to 1,500-1,600
7/ opened low side manifold knob expecting good things but no....
8/ low side pressure started reading at 70 psi
9/ after a few minutes low side pressure started building, first 70 psi, then 80....then 90.... closing in on 100 psi .... so I closed off manifold (low side valve), killed engine.
** I didn't catch the HIGH side psi reading as I worried about low side
** Ambient weather in DFW area on 25 June was about 40% humidity, 98 degrees F, (god I miss North County San Diego weather....)
I repeated my steps (1-9) 3 more times and got same results each time. ....didn't see cycling, the RPM's on engine would drop a bit on occasion but not what I see on my other runners when ac is cycling, not same load/rpm drop.
I put a high visibility mark on the ac clutch to check if it was spinning, again it would spin once then no more. when it spin low pressure psi reading are what you would expect/see when charging a system with r134a.....
I bypassed the new pressure switch by jumping the switch connector (using paper clip) - same patten, clutch engages, for 5-10 seconds, can see low pressure gauge drop down to say 20 psi, then clutch cuts off and will not reengage unless engine shut off then back on. i.e. one clutch engagement per engine on/off cycle.
At times, I could hear engine RPM drop slightly....but not what i see with my other runners when ac cycles/clutch engages and no movement on gauges (low side dropping to 20-25-30 psi for a normal charging cycle)
No idea why a new dense compressor clutch would kick on 1 time for 5-10 seconds, systems function as it should for those precious seconds then clutch doesn't engage again without resetting. Guessing issue on electrical circuit...
Could it be:
1/ AC amplifier switch failure?
2/ Too much PAG oil? Son thinks we may have put too much into system:
New Compressor had 3.9 oz - we drained new compressor then put back that amount - or did we add more - we didn't document ...
3/ per denso recommendations we added PAG : to condensor 1.4 oz, receiver, 0.70 oz, evap core 1.4 oz - trying to find an answer we are speculating that we may have added these amounts to the compressor in addition to the original 3.9 oz....essentially adding 2x the condenser, receiver and evap core volumes.
4/used Denso OD-Oil 8 (PAG 46)
Lord knows we missed something....Appreciate the help on this.
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