Newer 134 A/C versus good ole' R-12 - measured temps.

Discussion in '80-Series Tech' started by IdahoDoug, Jul 27, 2005.

  1. IdahoDoug

    IdahoDoug

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    Since a couple posts have appeared lately complaining about A/C systems not being able to handle heat, I did an instrumented test of my 80s today. One of the complaints has been that they work OK at freeway speeds, but in stop and go traffic several complain their system is healthy but cannot keep up with the heat and the air coming out the vents isn't as cold. I do not experience this on either of my 80s (though I'm not in 110 degree heat like some of you are - yowza!).

    Here's what I measured on a 94 degree day. Both truck cooling systems are as close to new as possible, with the 97 even having a new OEM radiator a couple months ago as PM. The temps were measured at the driver's window vents since testing showed it to be a couple degrees cooler on both trucks. Both on recirc, full cold, fully warmed engine and a/c on for at least 15 minutes, fan position #2.

    The 1993 blew 43.8 - 45.9 degree air at 70mph. At the end of the exit ramp (huge heat load), it blew 44.8 - 47.6 degrees. The range is simply when the compressor cycles on and off. In subsequent stop and go traffic, it blew 43.1 - 45.8 degrees. In full shade (my garage) it blew 42.8 - 45.7 degrees.

    The 1997 blew 45.6 - 47.5 degree air at 70mph. At the end of the exit ramp (huge heat load), it blew 46.8 - 48.3 degrees. In subsequent stop and go traffic, it blew 45.0 - 48.2 degrees. In full shade (my garage) it blew 46.9 - 49.4 degrees.

    When I stop at a traffic light, I personally cannot discern a difference in vent temperature and now that I've measured these, I'm not surprised. Both trucks blow ice cubes when needed, but clearly the older system seems a bit colder. They're both fully charged and I've cleaned both of the A/C condensors with my soaking technique to clear them of accumulated road grime and debris.

    The tool I used is a pricey MAC Tools digital thermometer designed with a probe for this purpose. I borrowed it from a mechanic at a nearby dealership.

    If you experience a loss of cooling at stop lights in this ambient temp range, consider taking a good look at your cooling system and your a/c system. You just might find things are not as healthy as you think, and a bit of PM could net you ice cold air.

    DougM
     
  2. Vitesse_6

    Vitesse_6

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    From what I know the R-12 compresses more then R-134, So that would/could be the differance, I will say that either way the LC's AC kick's plenty of patooty! I think it may have to do with the larger open space if you will of the vehicle, I dont have tinted window's yet and the AC in the 94 works great to cool it down ASAP.
    Nice write up just the same!
     
  3. Tools R Us

    Tools R Us

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    I agree that the Toyota A/C systems are one of the best, in most conditions they work great. All A/C systems deliver a certain temp drop, if you check the air intake temp under the glove box then the vent temp, you will see the split. The fact that your compressor was cycling shows that it was operating within it's capacity, a lot of trips in this climate the A/C will never cycle, run full blast the whole time. There is a point (somewhere around 110F?) where the system can't keep up and vent temps start going up.

    As an example, I went to deliver a load of tools to a client about 2PM the other day, got on the freeway and the radio said it was 114F. Sure enough got stuck in a traffic jam sitting in the middle of 5 lanes of stopped traffic. If its 114F in the shade how hot is the black asphalt? How much load was the A/C seeing from sitting in the sun? How much heat is coming off the other cars with their A/C running? The micro climate in that area was probably easily somewhere on the far side of 120F. Yes, the vent temps were affected, yes sweating was involved! My truck has 49K and it's last service before I bought it last year included a new blue hub fan clutch and a cooling system flush at the Lexus dealer. I would rate it to be in very good condition, the A/C has never cycled due to high side pressure or cooling system temp.

    My 4runner was not affected this way, but it had a factory electric A/C fan. I bet Toyota knows about this, that's why there is an electric fan and brackets, it's probably installed in all the trucks shipped to certain markets, middle east maybe?

    I don't have any temp numbers for you, all of my thermometers have LCD screen on them that turn black from the heat this time of the year if left in the truck and have to be cooled to read them! But I can't leave thermal print paper (gas receipts) in the console because they turn black! But it's a dry heat! :crybaby:
     
  4. Tools R Us

    Tools R Us

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    I have always cleaned the condenser and radiator, hose it out every carwash and remove the grill and thoroughly clean a couple of times a year. Cooling systems are important here if you don't want to walk! :D
     
  5. SteveH

    SteveH

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    While Toyota AC systems (such as in my 4Runner and 80 series) may run much longer without major component replacement, it would be hard to argue they out-cool anything found in a Ford truck or GM SUV. Those air conditioners will quickly make ice cubes in your lap - the Toyota systems require much more time. Japanese vehicles, IMO, frequently have AC systems that are fine for most uses, but are barely adequate when the temps go above 90. Their ability to knock down the temps in a hot car is where they show up most poorly - once the vehicle is cool, they usually keep up.
     
  6. Rich

    Rich

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    The hot non US climates not only got an ac condensor fan but also a second evaporator for the rear of the vehicle.
     
  7. IdahoDoug

    IdahoDoug

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    Just another data point for those of you with 93/94 models that get irritated (like me) at how much heat comes into the vent air when it's supposed to be cold/outside temp. This has always bothered me - it's a warm day, and the outside air coming in my window is fine, but at full cold (no a/c), the air coming out the vents is clearly heated. Grrr. Anyhow, I used the thermometer this morning to see what the difference is. Outside temp is 72 degrees, but at freeway speeds the vents are putting 80.5 degree air into the interior. This was done with the probe out the window for 5 minutes, then in the vent for 5 minutes. Interesting to see the outside air temp bounce around as you whiz down the road.

    DougM
     
  8. C6H12O6

    C6H12O6

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    I noticed the same irritating thing on my last road trip. I thought it was the Idaho air. I wonder if the air in the system is exposed to the heater cores as it just sits there with the fan off. That would make sense if the AC had to "purge" the hot air before the cool air starts.

    I've also noticed the floorboards are quite a bit hotter than the rest of the cab, almost as if the hot air is somehow getting out of the system somewhere down there. I'll have to get my fancy science teacher probes out and take some measurements to see if I can track it down. It doesn't seem to be hot floorboard syndrom like my old Ford Maverick.
     
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