L31MaxExpress
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About the same from what I can tell. I was a bit off with the previous CFM on the engine fan. Because I put a wrong unit of measurement into the calculator on mistake. What year is your truck.
Better AC with different size pulley?
- Thread starter JohnZ71
- Start date
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JohnZ71
I'm Awesome
2000 Z71 Tahoe OBS
Some discussion about leaks in the air handler, here:
www.gmt400.com
A/C Blower 1998 K1500
I have taken the dash apart and I had one door that wasn't in place. i have checked the actuators and they all seem to be working. The blower motor blows like crazy but the output through the vents seems about half of what it should be. It is not enough to keep you cool on a hot day. Ideas?
www.gmt400.com
L31MaxExpress
I'm Awesome
Something definitely sounds off with the setup. I never saw 320 psi on my 99 Tahoe or even my 97 Express without the pusher condenser fan here in Texas heat and humidity. The clutch fan should absolutely be roaring if you bring the engine up to 1,500-2,000 rpm on a 100F day. The only way you should even flirt with 275 psi much less 350 is at idle on a 100F day. Assuming you have the 11 bladed fan, the proper 34" wide condenser and the orifice tube im the right location. A rear air Tahoe should not have an orifice tube in the condenser although somehow a lot of them seem to get one installed there during AC repairs. Boggles my mind how many I have pulled out now and then found the OE one with the screen filled with trash from a previous comoressor failure. The OE condenser also cannot be flushed. I scrap them and put the more modern microtube parallel flow replacement into them.
That being said the early Duramax fan blade even with a bit of the blade tips trimmed to fit into my Express van shroud with the Hayden 4261 thermal fan clutch for a 2007 TBSS was the easiest and highest CFM fan setup I have run. It is aggressive and in very hot weather you will notice some power and mpg loss around town especially. At highway speeds it rarely ever engaged the fan past freewheeling unless I was towing uphill and the coolant temps got up around 205-210F.
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L31MaxExpress
I'm Awesome
I will also mention I have now experienced two failures of aftermarket clutches now in a year. A Hayden and Four Season. Both "severe" duty and both not moving much airflow at all until 210-220F of coolant temp. I put the GM 154672 clutch I mentioned earlier on both my aunts GMT400 based Escalade and my 1987 G20. The GM clutch was thicker, about 1/2" in diameter larger and moved about 2x the airflow of the aftermarket failures. After I replaced the clutch, before adding more refrigerant the 1987 G20 was not even hitting 200 psi in 102F ambient temp. I would start with measuring the condenser width, verifying the condenser and radiator are absolutely clean and no debris between them, and that the fan clutch is operating well. The anemometer I used was a $25 Amazon purchase and works fairly well for ball park CFM estimates. I am seeing ~5 mph of windspeed at 850 rpm dle and ~8+ mph at 1,250 rpm and over 10 mph at 2,000 across the grille with a properly functioning clutch fan.
Vettepilot
I'm Awesome
So, on cooling fans.
1994 GMC K1500 5.7. I installed a much larger and thicker radiator, and this truck has factory oil cooling. I am not a "fan" of fan cluthes (sorry for the pun), so I went with a factory style multi-bladed direct drive fan. It has numerous blades with a lot of pitch, (it's loud!). Engine flushed, hoses, water pump, etc., new. Condensor is new as well. Air dam is in place. The only weak point in my setup is that the fan could be 2" larger to fill the shroud better. Oh, 160 degree thermostat.
Anyway, yesterday I took it out in 115 +/- degree traffic, and the temp was climbing at stop lights. Really pissed me off. It never got close to boiling, but it hit 200. It would cool right back down once under way, but the temp climbing at a normal stop light interval is NOT what I am after!! It is borderline, and would be completely inadequate when the temps hit 125 here, or in freeway rush hour, stop and go traffic. You would be turning the A/C off and holding a fast idle to cool it. NOT GOOD!! My totally overhauled, expensive cooling system... SUX!
Comments, suggestions, fixes???
Thanx,
Vettepilot
1994 GMC K1500 5.7. I installed a much larger and thicker radiator, and this truck has factory oil cooling. I am not a "fan" of fan cluthes (sorry for the pun), so I went with a factory style multi-bladed direct drive fan. It has numerous blades with a lot of pitch, (it's loud!). Engine flushed, hoses, water pump, etc., new. Condensor is new as well. Air dam is in place. The only weak point in my setup is that the fan could be 2" larger to fill the shroud better. Oh, 160 degree thermostat.
Anyway, yesterday I took it out in 115 +/- degree traffic, and the temp was climbing at stop lights. Really pissed me off. It never got close to boiling, but it hit 200. It would cool right back down once under way, but the temp climbing at a normal stop light interval is NOT what I am after!! It is borderline, and would be completely inadequate when the temps hit 125 here, or in freeway rush hour, stop and go traffic. You would be turning the A/C off and holding a fast idle to cool it. NOT GOOD!! My totally overhauled, expensive cooling system... SUX!
Comments, suggestions, fixes???
Thanx,
Vettepilot
JohnZ71
I'm Awesome
Last year or so my Tahoe would start running hot at idle, turned out to be my condenser stopped up blocking a lot of the airflow.
after replacing that, it’ll idle all day long in the hottest sun and barely get over 200 degrees. My only issue is high head pressure with the AC lol. An enormous amount of heat is in the engine bay. Out of all the cars I have, this one has the hottest engine bay by far and I don’t know why. If I could cool down the engine bay, I know that’ll help my AC pressures.
JohnZ71
I'm Awesome
I should add that I have a 195 degree thermostat and the temp is almost always 180-190. Idling in the sun on a ~100 degree day gets it up near 200 degrees, which is nowhere near “too hot” imo.
What are you "after"?
@L31MaxExpress made some radiator airflow measurements w/an anemometer, you might want to do the same and compare to his. If yours is low by comparison, then you'll know where to focus.
Cooling the engine requires "temp rise" of the air through the radiator * "flow" of the air (anemometer measurement).
"Temp rise" is pretty low with a 160F 'stat in 115F ambient temp air (or higher, if pre-heated by AC condenser) at a stoplight. You engine's cooling system responded by increasing its temp.
I'm assuming the flow of coolant through your engine and radiator is adequate.
I've heard of people restricting or blocking the coolant flow to the heater core in order to route more coolant through the radiator where it can then shed heat.
I believe the L31 engines have an OE restriction in the coolant nipple / quick disconnect fitting on the intake, possibly for this reason. Others may comment.
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Vettepilot
I'm Awesome
Actually, I am not sure about the heater question. I have often wondered just how much the heater figures in to things. In overheat emergencies, which happen all too often during a life in the desert, we always turned the heater on high to try to suck some extra heat out of the motor.
In this case, it is a moot point, as I have the heater on a manual on/off valve. I do not want that hot water sitting in my A/C box.
What do I want? We really do have 125+ degree days here. Lots of them. Sometimes 115+ in the middle of the night. Manufacturer's extreme conditions testing ground is near here for a reason. Our cooling systems must be Super Duty +++. This is a stock engine-- no performance improvements such as headers or high compression that would complicate cooling.
I want enough cooling performance that it will sit at a long stoplight, and never go above the thermostat rating temp, with the A/C on and 120 degrees ambient temp.
It's not impossible; the cop cars idle for days without a "China Syndrome"!!
I am looking at handheld anemometers to check airflow. As I mentioned, there is room in my fan shroud for a larger diameter fan. How critical is that fit?? Could this be my problem?? Again, once traffic starts rolling, it cools right back down, but it's at 200+ and climbing at the stop.
Thanks,
Vettepilot
In this case, it is a moot point, as I have the heater on a manual on/off valve. I do not want that hot water sitting in my A/C box.
What do I want? We really do have 125+ degree days here. Lots of them. Sometimes 115+ in the middle of the night. Manufacturer's extreme conditions testing ground is near here for a reason. Our cooling systems must be Super Duty +++. This is a stock engine-- no performance improvements such as headers or high compression that would complicate cooling.
I want enough cooling performance that it will sit at a long stoplight, and never go above the thermostat rating temp, with the A/C on and 120 degrees ambient temp.
It's not impossible; the cop cars idle for days without a "China Syndrome"!!
I am looking at handheld anemometers to check airflow. As I mentioned, there is room in my fan shroud for a larger diameter fan. How critical is that fit?? Could this be my problem?? Again, once traffic starts rolling, it cools right back down, but it's at 200+ and climbing at the stop.
Thanks,
Vettepilot
