A Driver for one of our rental company customers was complaining of a broken A/C and no defroster. When the driver would try to turn on the defrosters it made a clicking noise.

The defroster is an essential part of a vehicles accessories, and therefore  must be operational to pass a CHP inspection.

Our mechanic started the job by removing the seats in the truck cab to allow better access to the dashboard. He then pulled the dash apart to gain access to the heater control box. This allowed him access to the blend door flap. That is where the issue was.

Have you seen the handy little dash tray that some trucks come with?

It sits right in center on the top of the dash board. It's so convenient for pens, change and other miscellaneous little items. Little items that can fall right through the defroster vents and cost the owner of the vehicle quite a bit of money in repairs.

This is where those "little items" end up. In the heater control box blend door area. The "little items" jammed the blend door and prevented it from opening up the defrosters. Eventually the gear drive broke from multiple attempts to open. The clicking noise the driver heard was the broken gear trying to catch.

In order to replace the broken gear, the entire heater box had to be purchased. There is a lot of labor involved in removing and replacing the entire heater box. The AC evaporator is inside the HVAC box and requires evacuation, removal and recharge of fluids upon re-installation. The temperature sensor, blower motor, actuators and resistor also need to be removed and reinstalled on the new HVAC box. In order to save our customers some money in labor, we removed the blend door and gear (interior parts to the left of the line below), and installed only those parts into the old HVAC unit. Now the customer has a spare HVAC box for the future!

Moral of the story:
Don't leave items on your dashboard! Even if there is a special tray just for it!

Back-Story: Previously a customer (let's say "Jim") had gone to the local dealer complaining of an engine miss. The dealer only cited one cylinder as having a miss. They changed ALL the injectors, and it still had a miss. The dealer guessed the engine fan was bad.  "Jim" brought his truck into M.D.S. and Chris tore apart the whole front end, looking for a vibration in the belts and pulleys. When that did not yield results, he went for the clutch. And there was the issue. The dual mass flywheel had gone out-of-round and was creating an engine miss feeling.

A different customer "Bob" came into the shop complaining of an engine miss. We preformed a cylinder contribution test- we found #1 cylinder contribution malfunction. We preformed cylinder cut-out test, still missing on #1. Bob was ready to have his injector replaced and Chris informed the customer of the clutch defect. Upon inspection and test runs, we found the clutch vibration. We advised Bob that a dual mass flywheel delete would prevent this in the future.

The job would be the same for 2 wheel drive or 4 wheel drive, it would just have additional labor for removal and re-installation of the transfer case.

Two weeks ago we completed a clutch conversion on a 2007 Dodge Ram 3500 2WD with a 6.7 Cummins engine. The truck comes stock with a dual mass flywheel and it was upgraded to a conventional flywheel. Dodge installs the dual mass flywheel to absorb more shock on take-off.