We get phone calls daily and several vehicles in each week in regards to H1 Hummers and overheating. One of the most common causes of your Hummer running warm and in some cases overheating is because of a clogged cooling stack. The unique 45 degree angle of the cooling stack allows for a debris to collect between the A/C Condenser and the Radiator. A quick inspection may not reveal whats buried on top of your radiator. The technician must be diligent and thorough with the inspection. It is best to unbolt the condenser from the cooling stack and carefully lift out of the way. Be extremely careful as A/C condenser is under pressure and can be harmful to both the technician and the environment if a line is cracked and refrigerant is lost.
If a clogged radiator is found, the top half of the cooling stack must be carefully removed so that full access can be obtained to the radiator. This can be done without disconnecting your coolers but again, care must be taken.
Once you have throughly cleaned your cooling stack, you should see a noticeable difference right away.