towing camper with '06 6.0 engine - issue

[bigbrad123]

I have a 06 chev 1500 max (heavy duty half-ton). I pull a 20 ft camper with it. I usually tow it in 3rd gear with the tow button on. While towing, I can hear something kicking in and out every 7 or 10 seconds that makes a lower pitched/louder noise. It almost seems like the truck is going into overdrive, but the RPM's aren't increasing or decreasing (staying about 3200 at about 70mph) and it shouldn't be doing it in 3rd with the tow button on, so I don't think it's overdrive. Could this be the A/C kicking in and out? The noise does get louder the faster I go (ie: if I get up to 75 mph), but the timing of when it does it stays the same. I just got the truck and have never pulled it with a 6.0 liter before.......I used to tow it with my 5.3 liter in 3rd gear and never remember hearing anything like this. Doesn't seem like anything is going wrong with it, the a/c works fine, it doesn't lose power, etc. Anyone have any ideas, or is it normal?

[iroc343]

Since you say it seems like it's going into overdrive, I wonder if it's the lock-up converter? It could also be the AC compressor, but the frequency seems excessive, unless the charge is low.

['00Z71,5.3RcabLbed]

My dad just had the fan clutch on his 8.1L replaced, when he pulled his trailer we noticed that it periodically would make a lot louder noise but the RPM's didn't change and the faster we went the louder it got. So it may be possible that the fan is what you are hearing.?? Just a thought.