Acura RSX A/C compressor overheats
Posted: Mon Jul 31, 2017 7:08 pm
New member here looking for help diagnosing the AC problem.
I have 2003 Acura RSX Base with AC compressor overheating. The car AC system was completely original until now; nothing have been replaced or fixed to my best knowledge. The AC worked fine until this year.
AC works fine and blows cold air when the car is cold. After some time the system starts blowing only hot air. The time until AC malfunctions greatly depends on outside temperature - if it is 70F or below it may work fine for my entire commute (1 hour); if outdoor is 80F it may run for 20 minutes then stop; if outside is 100F it may take just a few minutes before it stops blowing cold air. After some time (5-10 minutes) it starts blowing cold air again for another 5-10 minutes, then the cycle may repeat.
These cars have thermal protection device on the compressor and it is definitely trips cutting power to the compressor clutch coil. I measured voltage after compressor clutch relay and it is present (12V); measured voltage after the protection device and it is 0. I also tested the resistance between the thermal protector and ground (with coil in the circuit) and it is about 3 Ohm when compressor is cold and infinite when compressor is cold.
The compressor clutch relay and fuses are tested and good.
The low side pressure seems normal, around 30. The high side pressure is also seems normal on idle RPM, about 180. However when RPMs are increased to 2500-3000 the high side pressure starts to increase too, goes to about 250 and then thermal protector shuts off the compressor.
Here is what I did trying to fix the issue:
1. Replaced thermal protection sensor with brand new Honda part. No results.
2. Replaced condenser fan. The original one was working but seemed to rotate not fast enough. No results.
At this point I decided to open up the system and replace expansion valve suspecting it has stuck closed or partially closed. I had a local shop to evacuate the refrigerant. They said the system was low on refrigerant; they only evacuated 6 oz of refrigerant while the system capacity is 18-19 oz.
After evacuating R134A I did:
3. Replaced expansion valve
4. Replaced receiver/drier
5. Cleaned evaporator coil. It was not too dirty but I did that anyway
6. Replaced condenser as original was in rough condition after 14 years in service...
7. Cleaned radiator to make sure the airflow through radiator/condenser is not blocked.
8. Replaced radiator fan
When replacing the parts, I also used new o-rings everywhere and added PAG46 oil to new condenser and drier per service manual. Unfortunately I did not specifically checked for dirt inside the hoses/pipes and did not flush the hoses but I did not notice anything obvious. There is no visible dirt in the original expansion valve and unfortunately I did not keep the drier so I can't check if there was anything inside.
Once I finished with this I had the same shop to evacuate the system and charge it with correct amount of refrigerant.
The system worked fine for few days (it was relatively cool outdoors these days), but started to show the same issue again.
Checking it further I suspected leak in the low port service valve. It makes slight hissing sound every time I remove the cover cap. I brought the car to the shop which did the recharge and they agreed to replace both service port valve cores and recharge it again. When I picked the car up they said the system lost couple of ounces of refrigerant. To be honest, I doubt they actually did what they said because there was no any paperwork and the low service port still does that hissing sound when cap is removed, but maybe this is normal?
Anyway, still no results. The system still quickly overheats when outdoor temperature is above 70-80F. I even added the LED light connected to the compressor thermal protector so I can see how the system cycles the compressor while I am driving. When outside is below 70F it cycles compressor on for 8-10 seconds every 20 seconds and everything seem normal. However when outside is 80F and above the ON cycle time increases and eventually it stays on for a long time and compressor overheats again. When the LED signals the compressor in on but warm air blows the compressor clutch definitely not engaged; I confirmed by looking on it. It will engage again after few minutes at idle, but quickly disengages again.
I checked the evaporator temperature sensor thinking that it may have failed and caused evaporator to freeze up and block the refrigerant flow. It tested right in the entire temperature range from 32F to 86F. Also checked air mix door actuation motor and it is also good.
What else could cause the high side pressure to rise and compressor to overheat?
Thanks!
I have 2003 Acura RSX Base with AC compressor overheating. The car AC system was completely original until now; nothing have been replaced or fixed to my best knowledge. The AC worked fine until this year.
AC works fine and blows cold air when the car is cold. After some time the system starts blowing only hot air. The time until AC malfunctions greatly depends on outside temperature - if it is 70F or below it may work fine for my entire commute (1 hour); if outdoor is 80F it may run for 20 minutes then stop; if outside is 100F it may take just a few minutes before it stops blowing cold air. After some time (5-10 minutes) it starts blowing cold air again for another 5-10 minutes, then the cycle may repeat.
These cars have thermal protection device on the compressor and it is definitely trips cutting power to the compressor clutch coil. I measured voltage after compressor clutch relay and it is present (12V); measured voltage after the protection device and it is 0. I also tested the resistance between the thermal protector and ground (with coil in the circuit) and it is about 3 Ohm when compressor is cold and infinite when compressor is cold.
The compressor clutch relay and fuses are tested and good.
The low side pressure seems normal, around 30. The high side pressure is also seems normal on idle RPM, about 180. However when RPMs are increased to 2500-3000 the high side pressure starts to increase too, goes to about 250 and then thermal protector shuts off the compressor.
Here is what I did trying to fix the issue:
1. Replaced thermal protection sensor with brand new Honda part. No results.
2. Replaced condenser fan. The original one was working but seemed to rotate not fast enough. No results.
At this point I decided to open up the system and replace expansion valve suspecting it has stuck closed or partially closed. I had a local shop to evacuate the refrigerant. They said the system was low on refrigerant; they only evacuated 6 oz of refrigerant while the system capacity is 18-19 oz.
After evacuating R134A I did:
3. Replaced expansion valve
4. Replaced receiver/drier
5. Cleaned evaporator coil. It was not too dirty but I did that anyway
6. Replaced condenser as original was in rough condition after 14 years in service...
7. Cleaned radiator to make sure the airflow through radiator/condenser is not blocked.
8. Replaced radiator fan
When replacing the parts, I also used new o-rings everywhere and added PAG46 oil to new condenser and drier per service manual. Unfortunately I did not specifically checked for dirt inside the hoses/pipes and did not flush the hoses but I did not notice anything obvious. There is no visible dirt in the original expansion valve and unfortunately I did not keep the drier so I can't check if there was anything inside.
Once I finished with this I had the same shop to evacuate the system and charge it with correct amount of refrigerant.
The system worked fine for few days (it was relatively cool outdoors these days), but started to show the same issue again.
Checking it further I suspected leak in the low port service valve. It makes slight hissing sound every time I remove the cover cap. I brought the car to the shop which did the recharge and they agreed to replace both service port valve cores and recharge it again. When I picked the car up they said the system lost couple of ounces of refrigerant. To be honest, I doubt they actually did what they said because there was no any paperwork and the low service port still does that hissing sound when cap is removed, but maybe this is normal?
Anyway, still no results. The system still quickly overheats when outdoor temperature is above 70-80F. I even added the LED light connected to the compressor thermal protector so I can see how the system cycles the compressor while I am driving. When outside is below 70F it cycles compressor on for 8-10 seconds every 20 seconds and everything seem normal. However when outside is 80F and above the ON cycle time increases and eventually it stays on for a long time and compressor overheats again. When the LED signals the compressor in on but warm air blows the compressor clutch definitely not engaged; I confirmed by looking on it. It will engage again after few minutes at idle, but quickly disengages again.
I checked the evaporator temperature sensor thinking that it may have failed and caused evaporator to freeze up and block the refrigerant flow. It tested right in the entire temperature range from 32F to 86F. Also checked air mix door actuation motor and it is also good.
What else could cause the high side pressure to rise and compressor to overheat?
Thanks!