Hello. I am the proud owner of a 94 suburban. I rarely drive it (35,000 miles), but when I do, it provides humor for my two young daughters. As soon as I start the car, it begins making this tick/clicking noise right at the passenger side foot-well. It only lasts for about 30 seconds and goes away. It only comes back when driving, if I turn the A/C or heat on (again for 30 seconds). The A/C and heat work fine. The fun is when I turn off burby (as my youngest has named it), it tick/clicks for another 30 seconds with the key out of the ignition! Oh yeah, it also leaves a smell of oil on our clothes?not too bad, just enough to make no one want to ride with me. I welcome any suggestions and thanks in advance for your thoughts.
Perhaps there are leaves or other debris in the heater box that are contacting the blower squirrel cage.
I would recommend that you get the exhaust system inspected, particularly the catalytic converter. I think you have a crack in or near the converter.
Are you using a significant amount of oil? If not, do you get the oil changed at some regular interval? If you are burning oil, it could be leaking oil fumes from a crack in the catalytic converter, if you are leaking oil, which you may not see, it could be leaking onto the exhaust system and then burning off from the heat there. The clicking/ ticking could come from the oil burning at start up and again at shutdown when oil drips onto the pipes. For an oil leak like this, look for a leaking oil pressure switch of valve cover gasket.
I don’t know why the clicking would occur when turning on the heat/AC unless its a separate sound coming from the fan.
Some Chevy’s of that vintage used a stepper motor to position the HVAC Blend/Mode door that controls where the air comes from/goes to. When you start the engine, the stepper motor runs to select the source of air inlet and direct air to the appropriately selected vents. It runs on shutdown to close off the fresh air inlet. This is completely normal operation.
I don’t know why you would get the smell of oil on your clothes from that other than there is oil dripping on the engine/manifold, vaporizing, being injested by the fresh air intake and then dumped out the floor vents onto your pants leg.
have you been keeping a close eye on the radiator over flow tank? is it dropping? the smell you have may be a small leak in the heater core. to the uninitiated is may be confused with an “oil smell.”
if you put on the defrost is there a filmy smudge on the inside windshield glass? that would be a sure sign on a leaking heater core too.
BTW, a heater core leak can start out so small you barely notice the drop in level in the overflow tank. if you take this in for frequent oil changes and they ‘top up’ the coolant you may never notice the change in level.
Thank you very much!!!
Sounds like debris in the heater blower (as mentioned) As for the odor I found a plastic bag stuck to the cat once. Customer got three radios over it (swore the odor was from radio)