A/c not heating

Hi there, i have a crown hybrid with 2grfse3500cc engine. My a/c is not heating but when i refill my antifreeze by radiator cap it works fine. Antifreeze that i refilled is leaking by coolant reservoir. And when i open radiator cap it blows coolant and bubbling. So i thought it might be thermostat is not working. And i changed it and also radiator cap. But its still not working properly. What other reasons might it be? And i checked my oil cap but it was fine, cause i thought it might be head gasket is blown
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
If the cabin heater is not functioning, the most common causes of no cabin heat include malfunctioning blend door(s) (part of the in-dash ventilation network), a faulty or stuck heater control valve, a plugged heater core, stuck open engine cooling thermostat, collapsed hoses, and low coolant level. The cost to resolve the problem depends on which of the foregoing faults is the cause. If you desire a diagnostic to determine exactly why there is no cabin heat, please request a non functioning cabin heater diagnostic and the responding mechanic will come right to your location and get this resolved for you promptly.

If the vehicle is overheating, paradoxically that can cause no cabin heat as the boiling coolant generates air blockages in the system which can impede the flow of coolant to the heater core. The most common causes of overheating include low coolant level (including that due to sudden large leaks), a faulty thermostat, a plugged radiator, a faulty radiator pressure cap, collapsed hoses, non functioning cooling fans, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket or poor engine running condition can also cause overheating. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Engine overheating typically occurs if the engine cooling thermostat has failed, the water pump, or drive belt, has a problem, there`s a blockage in cooling passages, including through the radiator, cooling fans don`t work, the engine is out of tune, the head gasket(s) leak, coolant is leaking and thus the coolant …
Causes of this can be not having enough coolant, a broken thermostat, a damaged heater core bypass valve, or a blockage in the core itself. If you encounter any of these issues, you should never drive an overheating car. Have it towed to an auto shop if you must, but you never want to risk your car`s engine.
One of the most common reasons why your engine overheats when your AC is on is a faulty engine cooling fan, fan switch, or fan motor. A bad engine coolant sensor, an overloaded AC compressor, a broken water pump, and blocked AC condenser fins can also create overheating issues.
A common issue with central air conditioners occurs when they are working too long and hard, and as a result, overheat. Eventually, overheating of an A/C either will cause an internal breakdown or will trip the circuit breaker.
If there isn`t enough coolant in your system, the heater core will blow cold air into your car. Solution: If you confirm that a low coolant level is the source of your problem, you simply need to top off your coolant. You may want to check for leaks as well if you just recently refilled your coolant.
Step One to Reducing Engine Heat

The minute the temperature gauge starts to rise, turn off your vehicle`s air conditioner. The air conditioner can cause an engine to overheat quickly because it makes the engine work harder.

1. Turn on the heater. It sounds counterintuitive, but Reina recommends turning on the heater. It draws warmth away from the engine and into the passenger compartment, lessening the burden on the engine`s cooling system.
Can a Bad AC Compressor Cause My Car to Overheat? The compressor itself cannot cause the vehicle to get overheated. However, if the compressor clutch is engaged but the compressor is dragging to function properly, the extra strain on the engine can cause your car to overheat.
In general, wall and window air conditioning units with smaller capacities can typically run for up to eight hours at a time before they need to rest. Larger wall and window units have a longer running time of around 10 to 12 hours, depending on their cooling power.
You Have Cold Air Blowing Out The Vents When The Heat Is On Because of a Dirty Air Filter. Hiding in the filter of your heating system is dirt and debris. If you aren`t cleaning it regularly, this will accumulate over time, leading to problems with your heating system`s efficiency.
If you find that your car heater system is blowing air but that your car is not heating up: There could be a blockage or other problem stopping heated antifreeze from moving through the heater core component. A valve or switch could be faulty, or the heater core could be a clogged.
You`ll most likely hear a quiet clicking sound followed by air moving through the ductwork. You can also place your hand on a vent to feel for hot or cold air. If you don`t hear or feel anything within a minute or two of making the changes, your thermostat may need to be replaced.
Your car is overheating.

Lastly, a sure sign of a bad heater core is when your vehicle overheats. This could be due to a blown head gasket or a plugged heater core issue. Do not drive your vehicle if it continues to overheat, and make sure to bring it in to your local automotive repair shop as soon as possible!

Your Filter Is Dirty

A filthy filter is a common cause of a frozen air conditioner. In order to run properly, your AC unit needs adequate airflow, which is impeded when your air filter is dirty. If this is the case, you need to clean or replace it.

Dirty, clogged or overly restrictive filters may be the cause of many heating-and-cooling problems, including a constantly running AC system. What you can do: Turn your air conditioner off. Remove and inspect your HVAC filter.
However, running the a/c in the winter months does not cause any harm to the car`s heating and cooling system. In fact, there are many benefits to running the car`s air conditioning in the winter.
Your overheated engine may still be running, but it`s not fine. You risk costly damage to your engine if you keep driving. DON`T panic. Your engine may have lost its cool, but now is the time for you to keep yours!
The source of the issue could include a cooling system leak, faulty radiator fan, broken water pump, or clogged coolant hose. Regardless of the problem`s source, an overheating engine isn`t something you want to let linger. Your engine could sustain serious, if not permanent, damage.
The car air conditioner condenser is a radiator positioned between the car`s grille and the engine cooling radiator. Check the AC condenser first. If you see your car`s AC condenser is clogged or blocked, it will not work properly and will cause your car to overheat.
An overworked unit can cause you to feel uncomfortable. It may unable to cool your room evenly. Some spots may be too warm while the others are cool. This may happen because the unit is having a problem in replacing the hot air and circulating the cool air.
The constant running will reduce pressure in the cooling coil until it freezes over, which is dangerous as it can cause liquid refrigerant to flood back to the compressor and damage it (the compressor is a very expensive part).
When you turn the furnace on but no heat comes out, there may be an obstruction. Dirty air filters restrict airflow, which can make it feel like not much heated air is coming out of your vents. Check the furnace filter and replace it if its surface is covered with contaminants.
An electric heater that blows cold air could be caused by one or more of the following reasons: The manual reset has tripped. The fan switch is “on” and the thermostat setting is below the actual temperature. The fan is dispersing this air after shutdown.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

A/C and heat are not working properly. Car blows heat in summer and cool air in winter.
ANSWER : Common causes of no cabin heat include malfunctioning blend door(s) (part of the in-dash ventilation network), a faulty or stuck heater control valve, a plugged heater core, stuck open engine cooling thermostat, collapsed hoses, and low coolant level. The cost to resolve the problem depends on which of the foregoing faults is the cause. If you desire a diagnostic to determine exactly why there is no cabin heat, please request a non functioning cabin heater diagnostic and the responding mechanic will come right to your location and get this resolved for you promptly.

With regard to your air conditioning system, if merely re-charging the system restored normal operation but the a/c ceased to function after a month or so, that scenario typically suggests a leak. Some leaks are really cheap to repair, like if a couple o-rings need to be replaced in system piping but if the leak is at the compressor shaft seal, that repair is more costly. It is not expensive to find the leak and diagnose the system and once the leak is found the mechanic can let you know of the exact cost to repair the leak and re-charge the system. If you desire that service please request an a/c system diagnostic – suspected refrigerant leak and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you

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Heat inside car stays warm for minute then blows cold until I turn heat off for a minute and try again.
ANSWER : Hi there. The engine always at operating temperature leads me to believe, the thermostat is not the cause, for no heat inside the vehicle. There are several possibilities for no heat inside, the heater control valve is malfunctioning, the heater core is restricted, the temperature blend door actuator is malfunctioning. Replacing components without diagnoses, can be expensive and time consuming without resolution. I recommend having your vehicle’s inoperative heater be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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Car heat is cold until I add water and over heating with out telling me
ANSWER : Hello, thank you for writing in. There seems to be an issue that we need to take on first and foremost. This is the fact that you are having to add coolant to the system. This means the coolant is leaking either externally (onto the hot engine), or internally (being consumed with the air/fuel mixture). The best way to tell is to simply run the vehicle and watch for the leak. If the engine is consuming the coolant, you are likely seeing white smoke from the exhaust. This is most commonly resolved by replacing the head gasket. Common components to look for an external leak with are the thermostat and the water pump. Both would cause the symptoms you are explaining. Fore more help with the issue, contact our service department to schedule an appointment.

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My heat and air turns on without a problem but does not blow very hard (heat blows harder than air). Rattling noise.
ANSWER : The heater and the air conditioner both use the same blower motor. However, Nissan does have two separate fuses for the same unit. One of them can be blown. There are also resistors in the system that can fail. There are several electrical tests that can be done, but depending on the condition, it may be more practice to change the entire unit. Due to the age of your vehicle, and the Juke’s history of blower motor issues, it’s very likely a simple fuse issue. These can (for the most part) be visually inspected, and are cheap.

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Vehicle at running temp, turn on heat, no heat – stomp on gas, there is heat – ??? 2004 Jeep Liberty
ANSWER : Hello – regarding your lack of heater function unless the engine is revved up a bit, you have a coolant flow issue. This could be caused by a worn water pump (engine might be running warmer than normal?), a partially blocked heater control valve (adjustment problem or failed heater control switch), or clogged cooling system that simply has poor flow. I would recommend an inspection of the heater & cooling system by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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Heater not working reliably, is it caused by a bad thermostat?
ANSWER : From what you’ve described, it sounds like you have a stuck open thermostat. I’d recommend replacing the thermostat to see if this is the cause of the slow heat up of the vehicle since it’s a relatively quick repair. In an area like that it sounds like you’ll will need the heat in the winter very badly and as soon as possible. I would also recommend getting a coolant flush as it may help clear any possible blockage in the heater core. To avoid any unnecessary repairs, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose your heating issue and make the necessary repairs.

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Car won’t drive after over heating on the highway
ANSWER : Hi there. Most of the time when you overheat this engine it will also cause the transmission to get too hot. When this occurs it can easily cause transmission failure. I would suspect this if the vehicle does not move at all. If it move but is severely lacking power then you either have some serious internal engine damage or a failure in the catalytic converter from the overheating. It sounds like it is the transmission though. I would recommend having a transmission specialist take a look at it.

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Engine is over heating and I’m not getting heat. 2001 Pontiac Grand Am 3.4 V6
ANSWER : Hello – I agree with your diagnosis – a water pump failure is a prime candidate for both overheating and a "no heat from the heater". Lack of water flow will cause both symptoms, and cause damage to the engine in minutes. I would recommend a thorough examination of the cooling system immediately. A mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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