How cold should the air be out of the vent? [Expired Topic]

4202 Views 11 Replies 5 Participants Last post by GaryL, Jul 24, 2006

Shell

Discussion Starter · Jul 21, 2006

I have a 99 suburban. My a/c died on me last week. I had all new (not rebuilt) compressor, drier and expansion valve put in. But it doesn't get any colder than 58deg if the rear air is off and if it is on the temp jumps up to almost 70 deg. I know its been hotter than hades here (105) but shouldn't the air be colder and the whole suburban cool off with the front and rear air on? :?

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ChevyFan

· #2 · Jul 21, 2006

In theory, if everything was done right, the AC should be about the same as it was before. However, that being said, testing AC on a super hot day isn't necessarily easy becuase the compressor has to work overtime to get a decent temp.

I know of a guy who runs an HVAC shop and he says that the avg. AC unit will only cool a house to about 78F when it's over 100F outside. I would imagine that it would be similar for a car. ?? Does it get cooler in the evening or morning when the temp is maybe in the 80's or 90's?

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technojunkie

· #3 · Jul 21, 2006

I've heard....

It may be one of those urban legend kind of estimations, but I've heard that an average AC system (home or car) should be able to cool between 25-30 degrees from outside temps.

With the 100+ temps we've had here in Oklahoma, I've been pretty grateful for inside temps in of 78-82. Overnight it gets much colder as the outside temp drops to 85ish, but during the day, the system really has to work hard to get it down.

Does your Suburban have the "magic mirror" (as my kids are fond of calling it) that shows temp/compass?

If so - have you noticed the temp when you first start the truck? Once you get moving it cools off a bit, but mine has been starting at about 115 after a day in the sun.

(Whew!)

Good luck!

Tim the technojunkie

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ChevyFan

· #4 · Jul 21, 2006

I moved to Texas in 1999, and it was a record 2-3 year heat wave at that time. I made the mistake of leaving an un-opened coke inside my truck one hot day in September! WHOOPS. It was all over when I got outside later that day.

Yeah, I agree. That's how ACs work. It can only work so hard. A car is not as well insulated as a house is too.

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Shell

Discussion Starter · #5 · Jul 21, 2006

ac temp

It s not like it was befor. My kids would beg me to turn off the air because it froze them out. The only thing we didn't change is the condenser. I am supposed to be getting a new one today.

Right now the air is more humid than cool. I hope that solves the problem.

Thanks for the replies.

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nemopoppins

· #6 · Jul 22, 2006

My "magic mirror" temperature has a lot of trouble going up. When it has been sitting in the sun and not driven for several hours, it does start high. But where I live it's about 20-30 degrees colder than 5 miles away. When I leave my 50-60 degree temps, it takes forever for the temperature to change to the 80's or 90's. It's funny when it's been roasting for 20 minutes and my thermometer still says it's 60.

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GaryL

· #7 · Jul 22, 2006

Here's how the magic mirror works:

Here's from the service information's "Description and operation" of the mirror...

"In cold temperatures such as 3°C (37°F) or below, the temperature display will show ICE when the ignition is first turned ON. The display will toggle between ICE and the actual outside temperature until the temperature update process is complete."

And, here's the temperature update process. It's a little more complex than one might imagine...

"The inside rearview mirror has a temperature program that takes in account the fact that the radiator will heat the ambient air temperature sensor if the radiator is warm and the vehicle is not moving. If the vehicle has been off for more than 2 hours, the mirror temperature program assumes that the radiator has cooled and that the temperature supplied by the ambient air temperature sensor is accurate. Because of this, if the vehicle has been off for more than 2 hours, the mirror displays the temperature as reported by the ambient air temperature sensor. When the ambient air temperature sensor reports a new temperature to the mirror, one of the following cases will apply:

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is greater than the last temperature recorded by the mirror for 2 minutes. The mirror will increase the last temperature reading by one degree every 2 minutes for 8 consecutive times. If the outside temperature is not matched after the 8th update, the mirror will then display the current outside temperature.

• Ignition is off for more than 2 hours, then is turned ON for less than 3 minutes. The mirror will update the temperature display every 2 seconds.

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature.

• Ignition has been OFF for less than 2 hours. The outside temperature is greater than the last temperature recorded by the mirror, but the ignition is cycled from ON to OFF within 2 minutes. The mirror will display the old temperature.

• Ignition has been OFF for less than 2 hours. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature. "

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Shell

Discussion Starter · #8 · Jul 23, 2006

It was the condenser. When the compressor blew up, it clogged the condenser even though they cleaned it. WooHoo!!!! The air coming out directly from the ac vents is down to 38 deg. Sometimes better like once 34 and its been 95 deg today. I do have a meat type thermometer in the vent.

Thanks all

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GaryL

· #9 · Jul 24, 2006

Glad you got if fixed. Not a cheap fix, but at least it works now.

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nemopoppins

· #10 · Jul 24, 2006

GaryL, that was great stuff about the mirror. That explains my situation completely. So it's 16 minutes instead of the 20 I estimated. A couple of the points seemed repetitive, though, and I don't quite understand the one about the mirror updating the temperature display every two seconds when the ignition is turned on for less than 3 minutes. How would it know that?

Shell, good for you for fixing your A/C. It's been pretty necessary in these hot temperatures lately (not where I live but just about everywhere else).

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ChevyFan

· #11 · Jul 24, 2006

Glad that you got your AC cold again. I'm such a wimp nowdays I would die in Dallas w/o AC.

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GaryL

· #12 · Jul 24, 2006

nemopoppins said:
GaryL, that was great stuff about the mirror. That explains my situation completely. So it's 16 minutes instead of the 20 I estimated. A couple of the points seemed repetitive, though, and I don't quite understand the one about the mirror updating the temperature display every two seconds when the ignition is turned on for less than 3 minutes. How would it know that?

The best I can figure is that if it has been off for less than two hours, you can turn it on, then off, and then back on and it will act as a reset and forget about what it was reading before and try and figure out the current temperature.

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