Heating, Air Conditioning, Fridge, HVAC/Heater working intermittently


Hi, I have a concord 95% efficiency gas heater.]
Its been throwing this code, "Pressure switch open with inducer on"

I have a furnace that is working intermittently and I have tried almost everything to get the thing running again.  I have sucked out both intake and exhaust with a shop vac, made sure all the lines going from the inducer are clear and also cleared the tubes coming off of the pressure switch among other things.  One thing that I found that seems to get the furnace working is disconnecting the tubes on the pressure switch and then gently warming it up with a hair dryer and then reconnecting it.  After this the furnace fires right up, does this mean the pressure switch is bad or maybe water has somehow gotten inside of it?  I'm kind of pulling at strings at this point.  I have two kids under two and have been dealing with this for 2 weeks. It is about 10 degrees for the high here in northern ohio I have a few electric heaters as supplement its just very stressful trying to trouble shoot.

Thank you so much for checking out my post and for any advice!

Improper draining can cause pressure switch failures by plugging the hole(s) that provide the vacuum the switches need to close them. Even a momentary blockage will cause the unit to shut down.
In the case of a partially plugged drain, the unit would shut down and possibly lockout initially but once the water had drained low enough on units that will retry after one hour or other time depending on the manufacturer, would start again and run until the water build up tripped it again.
Signs of improper or partially plugged drains are gurgling or splashing noises in the vent motor or lots of water running out when drain tubes are removed from the secondary heat exchanger drain port.
Another problem to look out for is sagging in the vent pipe on longer runs or pressure switch hoses. Water will accumulate in these areas and work basically like a trap, causing a restriction of the pipe or tubing, resulting in pressure switch failures.
Many a technician has mistaken a venting or draining problem as just a bad pressure switch. Before condemning the pressure switch, check the required vacuum the switch needs to close on the pressure switch information sticker, then pull the pressure switch tubing from the power- Venter and put your manometer tube in its place. If the vacuum is less than the required amount to pull the switch in, it is not the pressure

Check the primary heat exchanger for signs of rusting, cracks, or deformities that could lead to CO issues. Because condensing furnaces produce acidic condensate, it is important to make sure there are no issues with drainage back into the primary heat exchanger, which can cause premature deterioration.

Check the secondary or condensing heat exchanger for any signs of leaking or blockage of the condensate drain. This may require flushing the heat exchanger, because the condensing heat exchanger has very tight passages for the air to move through. It is important to make sure that dust and build-up are removed to allow for proper airflow and that the filter is replaced on a regular basis;

The secondary heat exchanger is located directly above the indoor fan assembly.  

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.


Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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