AC only blows cold when driving vs idling

ANSWER : Hello, thank you for writing in. There are so many different codes being triggered, that it is unlikely all of these systems are having issues at once. We need to focus in on the fact the engine is overheating at all. You will want to check the level and condition of the coolant and the overflow tank. If the level is full then you may have an issue with the thermostat, radiator cap, or water pump. These can all be tested and changed relatively easily. If the main cooling system is okay, you will want to look into the heater core and climate control module. For more diagnostic help, contact our service department to schedule an appointment.

ANSWER : First, the coolant level should be checked to make sure the radiator is full. While the overflow tank may be full, the radiator cap must be taken off to check the level inside the radiator. If you find the level is very low, you have a coolant leak that must be fixed. If coolant levels are normal, an engine thermostat or heater control problem may be what you’re experiencing. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at your lack of heat concern to offer a more personal diagnosis.

ANSWER : If you are getting ready for a long trip and suspect the cooling fan may be not coming on for the radiator and a/c then you should have the a/c and cooling system performanced checked before trip. Nothing worse than breaking down when out of town in a strange area.

ANSWER : Hello. Thank you for writing in. The heating system depends heavily on the function of the cooling system. What is likely happening is a lack of coolant circulation when the car is idling. This is causing the coolant to sit stagnant and the heater has no supply of hot coolant coming into the heater core in order to heat the air coming in. It may be due to the water pump, which is tied into the drive belts. When the engine is running at a higher RPM the water pump may be functioning, and when the engine idles, there may not be enough power to work the pump. The pump is responsible for the flow of coolant, and is also a common place for leaks. Find the source of the leak, and test the pressure coming from the water pump.

ANSWER : Hi Allen. By far the best way to have your AC system correctly diagnosed is by having an AC inspection completed first. By having one of our professional mobile mechanics come to your location to diagnose the issue correctly, it significantly minimizes the mistakes in completing the wrong service. In your case, the issue could be as simple as needing to have the AC system recharged, or there is an existing leak that needs to be repaired before refilling the refrigerant. Best economic bet is to have the AC inspection completed first.

ANSWER : Hi there. It is possible that you have an obstruction of engine sludge or debris inside the heater core. This typically will cause elevated engine temperature and heaters to not work as well during operation; or specifically – when the heater control valve is opened during operation. It’s also possible that the heater control valve is not working as intended; which might explain the cooler air during engine operation. I would first suggest reading this article which explains some of the common symptoms of a failing heater control valve. If these are common with your issue, it’s probably best to have a professional mobile mechanic come to your location and complete a heater is not working inspection to determine the source of this issue.

ANSWER : Hello, thank you for writing in. There can be multiple problems with the vehicle causing your issues. First, we need to take a look at the drive belt which sends power to the AC system from the engine. When the engine is running at idle, the lower speed means less power going to the AC. As it stands now, the engine can not handle powering the wheels, and all the other components driven by the drive belt (alternator, water pump, air conditioning) at the same time. This may be due a slipping drive belt (failed belt tensioner, stretched out belt), a component drawing too much power from the engine, or other similar issues with the drive belt. Since the engine runs fine without the AC running, your engine is likely working fine. You should focus on the AC compressor (connected to the drive belt), the tension of the drive belt, and the condition of the other pulleys connected to the drive belt. For more help with diagnostics, contact our service department to schedule an appointment.

ANSWER : It is possible that you have a leak in the AC system. There are pressure switches that will turn off the compressor if the pressure is too high or too low. The low refrigerant level could cause the AC compressor to cycle on and off. If you would like to have this done, a certified technician from YourMechanic can come to your car’s location to diagnose the AC system and make the correct repair.