2005 LS2 A/C Belt Tensioner Rattle Problem
05-24-2017, 11:29 PM
#1
2005 LS2 A/C Belt Tensioner Rattle Problem
On my LS2, I hear an intermittent but pronounced rattle/hammering noise coming from the air conditioning belt tensioner. The tensioner flutters noticeably when making this sound. Here are more details, as well as what I’ve checked and replaced:
The sound only occurs with the engine at idle. Although occurring intermittently, it is sometimes rhythmic, occurring in bursts of about four seconds. At speeds above idle there is no flutter of the tensioner and no rattle.
The sound occurs independent of whether the car is hot or cold.
The noise is independent of whether the A/C compressor clutch is engaged (A/C on) or disengaged (freewheeling with A/C off).
The A/C compressor pulley turns easily and there are no rough spots that might indicate a bad bearing. The clutch engages and disengages as it should from the HVAC controls.
A/C performance is fine, all functions work and air blows cold.
There is no noticeable misalignment of either the accessory or A/C belts or pulleys and the harmonic balancer runs true with no wobble.
Using a mechanic’s stethoscope I detect no odd noises from the A/C compressor or other possible adjacent sources such as the block or heads or water pump or power steering pump.
I connected a GM Tech 2 scanner to the car and there are no Powertrain or HVAC system trouble codes present.
I have replaced the tensioner twice- once with a new one made overseas (from a parts store) and then with a new original GM/AC Delco unit (at $94).
I replaced the belt with a new one- same size as the original GM belt.
After all these diagnostics the noise still exists. Has anyone else experienced this problem and found a solution? Thanks in advance.
The sound only occurs with the engine at idle. Although occurring intermittently, it is sometimes rhythmic, occurring in bursts of about four seconds. At speeds above idle there is no flutter of the tensioner and no rattle.
The sound occurs independent of whether the car is hot or cold.
The noise is independent of whether the A/C compressor clutch is engaged (A/C on) or disengaged (freewheeling with A/C off).
The A/C compressor pulley turns easily and there are no rough spots that might indicate a bad bearing. The clutch engages and disengages as it should from the HVAC controls.
A/C performance is fine, all functions work and air blows cold.
There is no noticeable misalignment of either the accessory or A/C belts or pulleys and the harmonic balancer runs true with no wobble.
Using a mechanic’s stethoscope I detect no odd noises from the A/C compressor or other possible adjacent sources such as the block or heads or water pump or power steering pump.
I connected a GM Tech 2 scanner to the car and there are no Powertrain or HVAC system trouble codes present.
I have replaced the tensioner twice- once with a new one made overseas (from a parts store) and then with a new original GM/AC Delco unit (at $94).
I replaced the belt with a new one- same size as the original GM belt.
After all these diagnostics the noise still exists. Has anyone else experienced this problem and found a solution? Thanks in advance.
Last edited by snomuncher; 05-24-2017 at 11:33 PM.
05-25-2017, 10:24 AM
#2
Advanced
I have an 05 vert with same symptoms but very subtle in comparison to the HB chirping. I have replaced everything to include the balancer. The only thing not replaced is the AC tensioner. I will replace that next. I will let you know what I find in the next week as I am just happy to be rid of the chirping from the balancer. Best of luck and keep us posted.
