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jmstr
Dodge Dakota
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7/17/2006
17:31:29
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 Subject: What is coldest AC on 97 Dak?
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I am trying to fix my Dakota's AC during this heatwave. I can't seem to get it to blow colder than 55 degrees on max circulation with fan at max. Should I be able to see low 40s from the AC systems on our Dakota's?
Mine is a 1997 Dakota 3.9liter, and the air temp is around 97-107 degrees. When it is around 97 I can see high 50s on the AC, when it is around 107 it doesn't want to break 60. Oh, and the compressor rarely kicks on.
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TopCityDak
Dodge Dakota
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7/17/2006
21:48:12
| RE: What is coldest AC on 97 Dak?
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try this out. without running the air, get the engine up to operating temp. open both doors place thermomator in center vent. ac max with the blower on high. if the temp isnt 55* or colder(or 35-40* lower than outside temp) within 5 min you have a problem. during that 5 min if the compressior disengages, your low on 134a
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SteveJ
Dodge Dakota
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7/17/2006
23:34:52
| RE: What is coldest AC on 97 Dak?
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A/C systems remove heat from the air inside the vehicle, and give it up at the condenser just in front of the radiator. If the outside air is 70*F, the condenser will give up more heat than if the outside temperature is 100*F, because the coldest the condenser can make the refrigerant is outside air temperature. Refrigerant temperature affects the amount of cooling you'll get.
Here's some info I extracted from my 2004 FSM.
Match up the numbers - I couldn't paste the table.
Ambient Air Temperature:
1. 70
2. 80
3. 90
4. 100
5. 110
Maximum Allowable Air Temperature at Center Panel Outlet:
1. 45
2. 45
3. 55
4. 55
5. 64
High humidity affects cooling capacity as well.
One more thing. With the fan on maximum speed, the air is passing through the evaporator core too fast to give up much heat. Turn the fan speed down a notch or two as a test, and you'll see the air comes out the vents noticeably cooler, just without as much force.
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shatto
Dodge Dakota
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7/18/2006
01:06:02
| RE: What is coldest AC on 97 Dak?
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Just spent the day driving all over Sacramento in 105 degree heat. All day means running all day, shutting down for a total of no more than 15 minutes, during picking up stuff at 27 stops, over 200 miles.
I also spent over 40 minuted idling, in a parking garage, with the A/C keeping me comfortable. What is comfortable? 72.
Pretty much kept 25 degrees cooler inside than outside.
Fan- #3
Setting- Max.
Okay, it doesnt count because your 3.9 is a year older than my 3.9. And I have a standard cab.
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daffydak
GenIII
7/18/2006
01:27:29
| RE: What is coldest AC on 97 Dak?
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30-40 degrees below ambient is what you should expect the temp drop to be.. Dosen't sound like a problem to me, it's just HOT out where you are... How often does the compressor cycle? and for how long?
Dan
MOPAR=More Power!!
00 CC Sport Plus 4.7L 4X4 Auto, 3:55 LSD
Straight dual catack exhaust, adjusted tps to .76V, ported TB, home brew intake setup w/K&N filter, Superchips 3715 Tuner, 180* T-stat... more mods to come!!!
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BigEd
GenIII
7/18/2006
07:05:56
| RE: What is coldest AC on 97 Dak?
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StevenJ, the condenser does not make the refrigerant "colder" it makes the high pressure vapor (from the compressor) condense back into a liquid were it then moves as high pressure liquid to the evaporator were, at the expansion valve or cap tube, high pressure liquid is then reduced and evaporates, causeing a change of state, absorbing heat out of your cab of the truck. Then returns to the compressor as low pressure vapor and starts all over again.
Notice on the low side of your system in the engine bay, the suction line (line coming from the evap. in the truck) is cold and sweaty, this is were the heat is actually removed from the vehicle. It sounds weird, but thats how it is.
There, I'm done my Refrigeration 101 lesson for the day.
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jmstr
Dodge Dakota
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7/18/2006
12:02:06
| RE: What is coldest AC on 97 Dak?
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Thanks all, I think I'll just have to suffer with it the way it is in these 103 degree days. At 103 degrees outside the truck gets down to between 61 and 57 degrees. I guess that is the 'normal' range. Thanks for all the tips.
I just like my girlfriends' Toyota Camry better: it seems 10 degrees cooler, at least.
As for the compressor, it doesn't seem to cycle much right now. I haven't heard it recently, but it is hard to hear over the fan, when the windows are up and the floyd is playing.
I've also noticed the lower temps when the fan is slower. I just am greedy and want MORE cold than it pushes at setting one: even if it is in the mid 40s at 1 when it is around 57 on max fan [max cool for all of it, temps taken with thermo in the dash vent, other vents closed, windows up, rpm around 2000].
Thanks again to all for the tips.
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SteveJ
Dodge Dakota
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7/18/2006
13:59:12
| RE: What is coldest AC on 97 Dak?
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Big Ed. Perhaps I used the wrong words. The refrigerant gas gives up the heat of compression in the condenser to change state from a gas to a liquid. The condenser is in front of the radiator for this reason. Regardless, the refrigerant exiting the condenser will never be cooler than outside ambient temperature.
We're both right, just different perspectives on the process based on training and practical experience.
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BigEd
GenIII
7/18/2006
16:11:23
| RE: What is coldest AC on 97 Dak?
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SteveJ, your kinda on the right track, but it really doesnt matter what the temp of the liquid refrigerant is leaving the condenser as long as its high pressure liquid. it can be 40 outside or 100 outside, no differance as long as its high pressure liquid.
Whatever the btu rating of the a/c system is is what it will cool the vehichle to. That being said, if you have alot of leakage around your windows or whatever, you can expect your system to not cool as effectively as on another truck.
I totally agree with daffydak, jmstr has no problem, its just plain hot out.
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zzark
*GenII*
7/18/2006
20:35:49
| RE: What is coldest AC on 97 Dak?
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Use pipe insulation on the hoses.
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shatto
Dodge Dakota
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7/22/2006
00:44:58
| RE: What is coldest AC on 97 Dak?
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Steve J,
Something for you to calculate;
Thursday and Friday the temperature was 100 to 105 in Sacramento. I had 27 stops to pick up stuff all over, and I only shut the engine off a half-dozen times all day.
Inside temperature: 70.
Vent temp: 40 to 50.
Max setting, fan on 3.
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BigEd
GenIII
7/22/2006
10:34:13
|  RE: What is coldest AC on 97 Dak?
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Sounds like Shatto's is working great!!!!
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SteveJ
Dodge Dakota
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7/22/2006
13:50:37
| RE: What is coldest AC on 97 Dak?
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Yep. Nothing to calculate there, Shatto. Those numbers I posted are from the FSM and they're the max temps. Your output air is colder, and to echo BigEd's comment, your A/C is working great.
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TexasTodd
Dodge Dakota
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7/22/2006
16:43:58
|  RE: What is coldest AC on 97 Dak?
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Put a shut off valve in the intake of the water heater.
After I posted about this years ago, someone did an objective test, dropped the temp of the air from the vent 9 degrees F.
Works awesome!
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shatto
Dodge Dakota
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7/25/2006
01:30:49
| RE: What is coldest AC on 97 Dak?
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Jmstr,
Random thoughts:
1. Save money; whip out your vise grips and test what Texas Todd said.
2. Re; the Camry. Get off "feelings" and use a darn gauge. It is, however, true that if you feel comfortable it doesn't matter what the gauge says.
3. Does the compresser cycle? What-Is-The-Temperature-Inside? Focus.
4. A Texican ought to have tinted windows.
5. A big black towel, folded across the dashboard accomplishes; a)reduces glare. b)releases heat faster. Cab cools faster. c) saves the dash.
Lay some of that rubber stuff you (well, not YOU) line shelves with, under the towel and it'll stay put.
6. The only way I can think of to improve the A/C performance is to install an electric fan, to push/pull more air through at stop and go, commute speeds. You could simply hang it inside the shroud in front of the fan. The largest I found is 18" and the hole is 21" or so, but it might work. Jerry-rig it and see if it works first.
Out of randoms now.
Nite.
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BigEd
GenIII
7/25/2006
10:31:23
| RE: What is coldest AC on 97 Dak?
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Good job shatto, you need a job? The VA is hiring.
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