Scubaboo Posted October 31, 2022 Share Posted October 31, 2022 I just noticed parking after my usual weekend run that both radiator fans dont seem as noisy or powerful as I seem to remember them being. Car runs perfectly fine, no temp warnings on the cluster at all. I have a multigauge with a coolant temp sensor on the upper rad hose and an oil temp sensor on a sandwich plate, no overheating. AC works well also. Just checked and both fans go on when AC switched on. Looking for general operating parameters and troubleshooting advice, I'd like to check if the fan system is working properly before it causes problems. Especially interested in when the fans are supposed to go high speed and how to verify high speed operation. Link to comment Share on other sites More sharing options...
Scubaboo Posted October 31, 2022 Author Share Posted October 31, 2022 I see for some Subaru models the system is described as PWM controlled, and I see for others it is a simpler 2 speed system using 3 relays? I do recall someone mentioning to me here in an earlier thread that our models use relays to get 2 speeds? Basically, low speed is the 2 fans running in series so they have half the power, and high speed is when the ECU gives out a signal to activate additional relay/s to open an additional ground path so the fans now work in parallel and both run at full speed? If the theory is correct, checking it is still a bit over my head lol! Link to comment Share on other sites More sharing options...
FLlegacy Posted November 1, 2022 Share Posted November 1, 2022 Easy to check actually, turn the ac off and let the car run until the ecm calls for the fans to come on, they will come on at full speed when the ac is off. 1 Link to comment Share on other sites More sharing options...
Scubaboo Posted November 1, 2022 Author Share Posted November 1, 2022 Will try that. But I'd love to know more about the system to see if it isnoperating normally. I found some charts that detail the coolant and refrigerant pressures the fans will turn on to low and high for. Not sure if they apply to our cars. Will try to see if the coolant temps will match, I dont have a way to check refrigerant pressures while running though. https://www.sulegacy.com/inspection-1786.html Link to comment Share on other sites More sharing options...
motorbreath Posted November 2, 2022 Share Posted November 2, 2022 I had an issue a few years ago when I did not properly bleed the air out of my coolant system. The fans didn't engage even though the engine was getting very hot. After getting all of the air out they started working again, quite a stressful experience. I think there is a temperate sensor in the return line to the radiator, which at the top of the engine. I didn't have access to the coolant temperature at the time to confirm any of this, just my observations at the time. I always use a coolant bleeding kit since that experience... Anyway, in your case maybe there is an issue with this temperature sensor? A long shot, but something to check. 1 Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2022 Author Share Posted November 2, 2022 Hi, thanks for your insight! I think you are right, that is one thing to check. I will compare sensor temp to the independent multigauge coolant temp sensor, should be similar. Link to comment Share on other sites More sharing options...
motorbreath Posted November 2, 2022 Share Posted November 2, 2022 If you search this part number 22630AA140 at parts.subaru.com there is a useful drawing of the "water pipe assembly" where the sensor is definitely at one of the highest points in the coolant system. 1 Link to comment Share on other sites More sharing options...
Scubaboo Posted November 2, 2022 Author Share Posted November 2, 2022 (edited) Thanks for that, will check those diagrams too! EDIT: so that is where those are! Right at the front corner. Looks to be easy to physically check if the other parts like the AC lines dont get in the way. On a related note, I wonder if the other head has a similar port for a sensor, it would be neat for your standalone gauge to read from the mirror spot the factory sensor does. Edited November 2, 2022 by Scubaboo Link to comment Share on other sites More sharing options...
Scubaboo Posted November 13, 2022 Author Share Posted November 13, 2022 Well I've gotten oil temps to around 217 and coolant to about 212 with a few hard stoplight to stoplight pulls. At home I checked and the fan was on but on low. It did go to high briefly! I was at the rear getting stuff from the trunk when I heard the blowers switch. I had put the AC on LO and just waiting to see if it would do anything. I couldnt make it go high again after that though. Glad it still goes high but I feel it should be doing it more often. I havent been able to compare the OBD coolant temp vs the standalone gauge coolant temp reading. Link to comment Share on other sites More sharing options...
FLlegacy Posted November 14, 2022 Share Posted November 14, 2022 I don't know what your ambient temps are there, but here in Florida even on a 100 degree day the high speed rarely comes on with the AC running. I have to be idling in traffic probably 30-40 minutes before that happens. Link to comment Share on other sites More sharing options...
Scubaboo Posted November 14, 2022 Author Share Posted November 14, 2022 Its hot here, AC pretty much a necessity. Well, used the car again today and noticed high speed again so I am sure its working. Part of the reason I asked is that I am seeing higher temps on my multigauge setup, and I just started comparing OBD temps with my upper rad hose coolant temps. Turns out my OBD is 30-50f less than the multigauge. I am leaning towards a gauge issue at this point and not the car. Link to comment Share on other sites More sharing options...
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