Low propane pressure will cause poor cooling on LP. Having the tip burned off the swirl tube/flue baffle will also cause poor cooling on LP. As the other professional repairmen said, the only sure way to test a cooling unit is to take a 120VAC cord and wire it directly to the two wires going to the electric heating element. You are bypassing the entire control system. This test is done after you have placed your OHM meter on the two wires going to the electric heating element to verify you have 40-49 ohms. Run the test for 24 hours. Keep a close eye of the unit during the test, you have bypassed all the safety features.