AC Performance

My 99 avalon has better ac than my 19 tundra

 

I never have felt like it's lacking but my 02 ranger was an absolute beast, almost instantly an icebox, rarely past 2nd speed out of the 4.

 

This app has opened up a new world for me. I grabbed this data from my 20 minute drive home from work, then some sitting in the parking lot.

1 - Drive home from work, high RPMS, high airflow, evaporator temp cycling between 33 & 44. I am interpreting this as the compressor cycling on and off.
2 - Stopped in parking lot, low RPMs, low airflow, temp starts to climb, does not cycle in the same way it was when driving.
3 - Rev up to 1200RPM, still in park, you can see the compressor cycling again from the temperatures as well as the RPM spikes.
4 - Idling in park, temperature rises, AC is blowing noticeably warmer in cab, ambient temp sensor is rising as engine bay temps go up
5 - High idle again in park, get the compressor to cycle twice, but much slower
6 - Put the truck in drive, but apply no gas, still low RMPs, only increasing airflow thru condenser and engine bay. Compressor starts to cycle again just like when driving high speed/high rpm. Max speed 10mph


I still have to do more testing but these results are pointing me towards it being an airflow issue. My fan clutch did not seem to activate once while sitting idling (note its 95deg here in Tampa today). I might have a fan clutch issue. Otherwise I think I benefit from an electric aux fan mounted in front of the condenser to push more air through. I think even a small one will help considerably. I do not think my high-idle switch is helping as much as I thought it would .

I am not an AC expert but I think the crux of the issue is that the condenser is not cooling the 'freon' fast enough to trigger the pressure switch to allow the next cycle to begin. With the extra airflow it cools faster, builds pressure, and cycles quickly.

Would love to hear additional input on this. I am going to be looking more into testing my fan clutch first and foremost.

PS. I know this all may seem dramatic, but on a 110degree day in FL not being able to retreat to an idling truck on the worksite is a major pain. Even if we're just talking 10 or 20 degrees it's a large difference. (Also it's just fun to tinker with this stuff)

 

Starting to think fan clutch may be my issue. Truck has 200k miles on it. Might be due for a new one. I never hear it roar in high temps even in the middle of FL summer.

 

Have you noticed a mileage drop at all?

 

I don't track milage at all. I also idle a lot so it's hard to guage. Though, on a recent highway trip I reset the guage and was getting about 17mpg cruising on the highway. With a leveling kit and 33s.

 

Try the paper test. You should be able to put a piece of paper in front of the ac condenser and it not fall. The fan should hold it in place. Make sure it doesn’t slip through. This would be easy since your grill raises with the hood.

Also saw this:
To confirm the diagnosis, start with this simple test: Spin the fan as hard as you can on an engine that has not been started that day.If the fan rotates more than five times, you can bet the clutch is bad.

 

Pretty sure it will pass this test, if memory serves correctly I can feel the air being drawn in even with the hood down. But I will try it. I wish there was a better way to test the fan clutch. I might pick up a tachometer and see if I can see the RPMs change as it engages and disengages. I hear a roar when the truck starts up but after that I can't hear any difference.

 

Passes the paper test easily. Spins less than 1/4 turn by hand when hot. Stops immediately when hot engine stops. No freewheeling.

 

My 01 4Runner with an Original, unopened a/c (ever) and 339,600 miles cranks out 36 degrees at the vents. It could have been parked in full sun in 105 temps, jump in and within 10 mins you will be lowering the fan speed.

Best A/C I've ever had, i especially like the mid-steering shaft vent (crotch cooler), haha.

 

I put a thermometer '13 Limited with auto AC on a 98 degree day. Sitting in the sun, it read 110 before starting. When I started it, the AC came on in a few seconds with full force fan and automatically in recirc. Within a minute, the thermometer read 60, and two minutes later was at 40 sitting at idle. That's about where it leveled out. Went slightly below 40 while driving. Fan starts to turn down wihin a few minutes. Only moderately humid today.

 

If your fan clutch isn't engaging when you'd like, you can take it apart and change the oil in it to a thicker/thinner grade. I can dig up the info for it tomorrow when I get some free time. I don't remember all the details

Edit: This should prove helpful, if our fan clutches operate the same, which I suppose they do. Seems like a cheap, easy experiment. Other than removing/installing the fan clutch multiple times to get it dialed in the way you want.

 

I saw this and was considering this. Thanks for the link.


I ordered a new Haynes heavy duty clutch. I don't want to mess around with taking it in and out multiple times. And it's possible that the thermospring is malfunctioning. For $100 it's worth it for peace of mind.

 

The slower the fan speed, the colder the air will be coming out of the vents. I usually run mine not more than 3/4 at first and wait a few minutes before I turn on recirc. If you start with recirc on at first, you are just recirculating air temp that is hotter than outside.
Running the fan at full blast at first, doesn’t give the air much time to come in contact with the coil to pick up the cold air. Hope this makes sense

 

Makes sense, tell it to Toyota. Recirc and full fan speed are on from the get-go on the auto-AC. Yes, if it's hot enough and the truck has been parked in the sun. I'll manually turn the recirc off and crack a window. But I don't turn the fan down. The sooner I can exhaust the hot air, the better. Besides, my point was that my AC is as good as anything I've ever driven. If it's pumping out 36° air at full fan speed, why would I bitch?

 

Installed a new fan clutch yesterday. Waiting for a hot enough day to see if it solves my issues. I think the next step will be auxiliary electric fan.

In "normal" conditions it is doing fine (temp reading ~40deg at the coil from OBD readout). The only time there has been an issue is on high heat/humidity days in Tampa FL summer ONLY while the truck is not in motion. This is why I think auxiliary fans may help.

Quick notes for anyone changing their fan clutch

• Part is about $100
• You need to disconnect the upper radiator hose to remove the fan shroud and fan together
• I spilled about half a gallon of coolant disconnecting this
• You cannot do this job without removing fan shroud
• Let engine cool 100%, its tight and you will burn yourself otherwise
• Job can take under 1hr if properly prepared
• 4 nuts on clutch and 4 nuts on the fan, 2 bolts on fan shroud, 1 clamp on upper radiator hose to deal with.

 

New fan clutch helped a smidge, but today in tampa 100deg I still struggled to keep the coil cool at idle. After reading this thread on tacoma forums https://www.tacomaworld.com/threads/a-c-condenser-fan.239576/ I'm pulling the trigger on 2 - 10" fans from Amazon. Only $40 shipped, worth a shot. The tacomaworld thread is interesting as it talks about how in the Mexican market the tacomas were factory equipped with electric aux fans. I will start by placing them on an in cab switch to turn on manually. Planning on only running them on 90deg+ days. Some people talk about wiring into a relay with the fan clutch but I don't like the idea of them running all the time, especially on the highway. With a button I will be in control and be able to do more testing on how effective it is.

Also, should be getting the front windshield tinted this week. That should help with the initial cab cooling. It seems from my testing that it takes a certain amount of time to reach 'equilibrium' inside the cooling system as parts cool down from baking in the sun, even straight on the highway it takes the system a while to get cycling regularly.

 

Some light reading for those following along: http://cf.linnbenton.edu/eit/auto/ehlersr/upload/752 Handbook.pdf Toyota Air Conditioning and Climate Control Course

Electric Fans will go in in a few hours.