383 motor swap in a 2001 Suburban 2500 4x4 chassis. I did the original swap with the clutch fan setup, and the AC worked fine.

About 6 months later, I did the efan swap. The primary reason for the efans was to improve AC performance while sitting in slow traffic. I used the following:
- OEM style fans from Rock Auto
- Nelson harness
- Fans turned on by Justin at BB

Ever since then, the AC cycles on and off about every 2-3 minutes. It won't stay cold because of this. Also, 2 belts have broken in less than 2 years.

Anyone ever seen anything like this before?

 

Ac usually cycles on and off when the pressure in the line is low, or faulty pressure sensor.

 

pressure rising, to hot can't cool the freon back to a gas ?
low or hi freon charge ?

 

i'd look into the tune. maybe bump the idle a hair and there are some idle adjustments that can be played with in AC on/off section of the tune. does your rpm drop when the A/C cycles?

i think the clutch fan is more dependable and does a better job than any e-fan on these trucks. just my opinion.

 

I disagree, the Tahoe E-fans are MUCH BETTER than the mechanical clutch fans at slow engine speeds.

My Express idles at 750 rpm and I have a 25% underdrive on the crank. My CS-144 140a alternator has an overdrive pulley on it but is still only marginal for keeping the voltage up. I plan to switch to a Napa 200a AD-244 soon and upgrade the wiring. A/C was blowing 38-40*F yesterday and it was 95*F outside. The engine never gets over 178*F with a 170*F thermostat.
IDLE


Stationary @ 2,200 rpm


The E-Fans are not your problem, although the calibration certainly could be. You could be cycling on the high side cut-off. I would check for an overcharged a/c system.

How does it cool going down the road at 50-60+ MPH???? E-Fans should not even be running at that speed as the vehicle will have plenty of airflow through the radiator and condenser to not even need a fan. Also check to make sure the connectors of the fan match the motor correctly and you are pulling air rather than pushing air. If you are pushing air through the radiator and into the condenser that would explain the poor cooling.

 

Sounds like you may be low on refrigerant charge, and you bought cheap belts.

 

My sister had a 2003 Tahoe that snapped the a/c belt on a road trip in CA. Turned out here compressor clutch bearing was seizing up when it cycled on, snapping the belt.

 

That is another possibility, but is usually accompanied by some bearing & pulley noise.

 

Thanks for all the comments.

Since the AC worked fine before the efan swap, I'm inclined to think the freon charge is OK, but I don't know for sure.

Tune is certainly a possibility. I already had to get Patrick G to fix something that the BB tune screwed up (related to the TPS) so another tuning error by BB would not surprise me.

The clutch fan is fine, but at idle speeds the efans move a lot more air.

Cooling at highway speeds is ice cold - until the belt breaks.

I use Gates P/N: K040378.

I will check for that, thanks.

no noise that I can hear.

 

There is 1 other thing that is rare but could cause a similar issue.

Look at TSB 03-01-38-019A

We had a stock Suburban with a mechanical clutch do the same thing. It would snap/ shred the belt or break the tensioner. There was no noise after replacing the tensioner. 3 tensioners and 2 belts later we found this TSB. We flushed the AC lines and replaced the AC compressor.

I wanna say we put some gauges on it to verify there was an issue.

Either way Getting a set on there would be a good way to rule out the Mechanical side of things.

I ask that you dont post the tune on the open forum. but do you have a copy of the tune file or do you have a cable to read the tune file?

If so, take a screenshot of the settings. If not, ask your current tuner to look into these settings and see if he spots anything obvious.