Carrier Gas Pack Problem

______________________________________________________________________ Our house is equipped with a Carrier gas pack. It is a self contained air conditioner with a gas burner added for heat that fits in a single enclosure. It is mounted on a pad outside the house and heated/cooled air is fed inside via ductwork in the crawlspace. In our case, the gas is propane. The Carrier model number is 48SS-042100321. The unit is about ten or eleven years old. We have owned the property about 2-1/2 years. When we bought the house, we replaced the standard wall thermostat with a Honeywell CT3600 programmable thermostat. All worked well until recently. The unit was professionally serviced at the start of this heating season. Recently we began having two problems, possibly unrelated. 1. There is a a burning smell coming from the vents. This has persisted for several weeks. Sometimes it is strong; sometimes it is barely detectable. It does not set off the smoke or CO detectors. 2. The blower motor comes on erratically during non-heat times. Sometimes it literally pulses every few seconds. Sometimes it runs for a minute or two, then shuts off. Sometimes it runs for quite awhile before shutting off. Twice it has failed to shut off at all. In the two instances that it did not shut off at all, we woke up to no heat the next morning. Tripping the AC breaker for a few seconds cleared the no heat problem. After that, we found that tripping the breaker seems to cause the blower motor cycling to stop for quite a long time, but eventually it always starts back up a few hours later. The thermostat fan switch is set to auto and has been cycled, just in case. Setting the heat to Off has no effect on the blower if it is already running. We called a service tech out for the fan and burning smell problems, but it was before we discovered that disconnecting the AC has a resetting effect. It was also before we lost heat. He could find nothing wrong and said he thought the burning smell was from mice that had gotten into the duct work–and there is evidence that they had been chewing on the ducts. He diagnosed the fan issues as probably mice chewing on the wiring between the thermostat and the unit. He did not take the top off of the unit to gain access to the heat exchanger or blower area. It was left up to me to patch the ductwork and chase down the wiring under the house to look for any place the mice might have chewed on. Considering that the smell is still strong after this amount of time has passed, I have my doubts that it is something as simple as a dead mouse in the heat exchanger area. The resetting behavior seems to rule out the mice as culprits for the blower problems, too. The tech examined the control board in the unit and could find no evidence of burning or anything else untoward. At this time, I have not gone under the house to look at the wiring, as it is difficult, and I am pretty sure the problem is in the unit. We are in a rural area and the tech is the only one in the book who lists himself as an authorized carrier service person. I am concerned that this may turn into a rather expensive repair on a unit that is nearing the end of its service life. Propane has skyrocketed in this area, and the suppliers are not optimistic about the long term price structure of their product. I have it in the back of my mind to try and get by the rest of the heating season, which shouldn’t be too long here, and then replace the whole shebang with a high efficiency heat pump. This is TVA territory, so electricity prices are fairly reasonable. Any opinions on all this and/or recommendations as to how to proceed would be appreciated. Thanks to all for taking time to consider this. ————————————————————— Heard a lot lately — “You want HOW MUCH for propane?” [this message was edited by PropaneBurner on Sun 27 Feb 22:32] Replies: Freon “Re(1):Carrier Gas Pack Problem” , posted Mon 28 Feb 13:33 ______________________________________________________________________ First thing I’d do is grab a bright flashlight (new batteries), go out to the unit, open all the access panels and inspect it closely. I’d use your nose and sniff everywhere, especially at the main blower motor. The erratic blower behavior could be related to some kind of slow electrical failure–capacitor or motor windings. I’d also look at the inducer motor, if there is one. I am assuming the smell is from material other than a mouse or other flesh that’s burning or getting excessively hot. If it were a rodent, by now the smell should have dissipated. Your nose will be your best tool as well as sharp eyes looking for anything dark or burned. PropaneBurner “Re(2):Carrier Gas Pack Problem” , posted Mon 28 Feb 14:45 ______________________________________________________________________ Thanks for the response, Freon. I realize that I should have added that the burning smell is only present when the heat is actually on and the burner is going. There is no odor whatsover when the blower is operating when it should be off. I will pull the top cover and check inside the heat exchanger/blower compartment myself. —————————————————————- Heard a lot lately — “You want HOW MUCH for propane?”