Test the pressure switch: Use a multimeter to test the continuity of the pressure switch. With the HVAC system off, the switch should be open (no continuity). When the system is on and operating at the correct pressure, the switch should close (show continuity).
Check the pressure gauge on your plumbing system. If it reads below 40 PSI, the pump should be actively working to change that. If the pump isn't turning on despite a severely low reading, the pressure switch may be at fault.
Pressure switches eventually go bad, it'll fail and your pump will not start and stop correctly. I've seen pumps/motors burn up because the switch fails. Then what could've been a 30 dollar fix (switch cost) turns into hundreds, if not thousands of dollars in repairs.
The useful life of a pressure switch typically ranges from 5 to 10 years, depending on its usage and maintenance. Frequent pressure fluctuations or harsh environmental conditions may shorten its lifespan. Regular maintenance and timely replacements can extend its operational life.
Electrical Issues
The pressure switch itself can sometimes get overloaded due to a power surge and burn out. In this situation, the only option is to have the switch replaced. More commonly the switch will fail due to a loose electrical connection.
The average cost for replacing an AC pressure switch, including installation, ranges from $150 to $400. The price for the part alone generally falls between $10 to $60. If your AC pressure switch is still under warranty, you're in luck. The cost for a replacement can range between $100 to $300.
The pressure switch can last for several years, but sometimes it can fail much sooner than you expect. To avoid being left without a functioning well, some homeowners simply have the switch replaced every year. Your well pump contractor can make this replacement when they come out for their yearly maintenance visit.
For a single level home or a two story home without water fixtures on the 2nd floor a 30/50 PSI setting may be sufficient. For two or more levels with water fixtures on more than one level you may want to use 40/60 PSI setting. It's easier for a pump to supply the lower pressures and it's less strain on old plumbing.
Damaged or dirty components, regular wear and tear, and electrical disconnections are some of the most common switch triggers. Quality Heating, Cooling & Plumbing also answers other pertinent HVAC questions, including, “Is it bad to turn your furnace on and off?”
Start by disconnecting one of the wires from the pressure switch. Connect the jumper wire: From here, you can connect your disconnected wire to your jumper wire. Turn on the furnace: Once connected, attempt to turn the furnace on. With the jumper wire connected, you've successfully bypassed the pressure switch.
The good news? Replacing the pressure switch is cheap and only takes about an hour. Diagnose a cranky switch by rapping on it with a screwdriver handle. If the pump runs (you'll hear it click) or quits, you've nailed the problem.
Set a multimeter to test for resistance (ohms). Touch each tester probe to one of the switch terminals. The pressure switch tester should read 0 or close to 0 (indicating no resistance). If the reading is higher, the switch has failed and must be replaced by a qualified technician.
If the AC pressure switch is faulty, it may cause the compressor to turn on and off rapidly. This is short-cycling. It can cause the AC system to work inefficiently and increase wear and tear on the compressor. To prevent higher cooling costs, schedule an AC repair immediately.
Direct motor wiring: A problem one may often see is wiring directly to the compressor motor, bypassing the pressure switch. This bypass disrupts the switch's control over the motor, resulting in it continuously running regardless of the system's pressure.
The AC pressure switch is responsible for turning the system on and off in response to changes in pressure. If the switch is malfunctioning, it can cause the system to stay on when it should be off or vice versa. This can lead to a buildup of heat inside the unit, which will eventually blow into the room as warm air.
If correctly sized, properly installed, and well-maintained, the average furnace will last about 15 to 20 years. Comparatively, the maximum life span of a furnace pressure switch is about 10 years.
A faulty low-pressure switch will lead to a damaged compressor, as the system can't control the pressure. So, if your AC is not blowing cool air to your space, you might want to check out that switch. If your unit keeps turning on and off, there is a significant possibility of a problem with the AC low-pressure switch.
If your pump doesn't activate when the water pressure drops below the cut-in level, the pressure switch could be defective or disconnected. Inspect the wiring and switch contacts. If these look fine, consult a repair service to test and replace the switch.
Bypassing the low-pressure switch is a temporary solution, and it's important to understand that seeking professional assistance for a permanent fix is recommended. Regular maintenance and professional inspections will help identify and address the root causes of low-pressure issues.
A bad switch, or a tripped switch, is a common cause of furnace malfunctions. Pressure switches may act up for several reasons, including: Old age, which can cause inaccurate readings and faulty furnace cycling. Coated or stiffened pressure switch diaphragm. Holes, tears, or other damage to the diaphragm.