What Could Be The Problem? My car has no heat.

My Car Has No Heat Only Blows Out Cold Air But Is Not Overheating

My car has 240000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
This may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your heater core.

How to Identify and Fix Common car Problems ?

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

The most common reasons a Volkswagen Passat heater isn`t working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor. Search our network of RepairPal Certified shops near you to speak with a technician about your issue. Oops! We got lost!
Common Car Heater Problems

The heater switching system might be faulty. The cabin air filter might be choked, restricting the airflow through the heater core. The thermostat valve might not be working right. The heater core might be clogged.

Low coolant: Whether caused by a leak or water evaporation, low coolant is the most common source of poor heater output. Thermostat: A stuck-open thermostat prevents the engine (and coolant) from heating up. Heater core: A clogged heater core restricts coolant flow, giving up little or no heat.
If one or more of these issues is present, your vehicle may blow out cool air rather than heat: Not enough coolant in the engine. Problems with the heater core. Clogged or broken heating controls.
If your heater doesn`t start, chances are the problem stems from having a dirty furnace. Having dirt on your blower motor or flamer sensor could render your furnace unable to perform. When the blower motor is too dirty, it won`t pass enough cool air to the heat exchanger, leading to equipment failure.
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.
If you think the cause for your car heating not working is related to the blower fuse, be sure to replace it with one of the same amperage. The fuse may have blown due to age, or it may suggest an underlying problem. If the replacement fuse (of the same amperage) does not blow, you may well have identified the problem.
Clean Filters

One of the most common issues with a heating system not functioning is dirty air filters. If your air filters are extremely dirty, then the airflow can be blocked. Check for clean air filters, vents, and registers. Make sure there are no rugs or furniture blocking vents or registers as well.

Diagnosis. There are two main reasons for this. Either there is a problem with the thermostat in the heating system or the heater core has a blockage or air in it. To see which of these two problems is causing the fault, drive your car for a while and get it up to its working temperature.
If just one (or a few) of your radiators aren`t heating up, the most common reason for this is trapped air. If you`ve just turned the heating back on after the summer, air can become trapped in your radiators, causing them to be warm at the bottom but cold at the top.
If your radiators are not getting hot enough it could be that they are full of sludge, the older your central heating system is, the more likely it is you have sludge in your radiators A good way to tell this is by seeing if they`re only warm at the top, this would mean that the radiators are only working at half power …

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

Battery and oil light come on when trying to start car, take keys out try again car starts no problem and lights go away
ANSWER : Of course, don’t switch gears without being fully stopped, unless your Owner’s Manual or the manufacturer has alternative advice. However, the gear shift issue has no relation to the no-start problem you are describing. Inasmuch as you only have 6,000 miles on the car, the "constant on and off" that you believe has occurred is meaningless in comparison to the expected total vehicle service life. That is, assume what you perceive as "constant on and off", during merely 6,000 miles, might be equivalent to using the car "normally" for three years. A new car should be trouble free for at least 5 years, unless there is a defect, so your "constant on and off" is not a causal factor for any fault on the vehicle. What you might have is a defect in the ignition switch, or perhaps the immobilizer system, but if the problem is not in the switch itself, clearly there is an electrical problem.

If your vehicle is under warranty, by law the dealer MUST repair the issue you are describing within a prescribed time frame and number of "attempts", otherwise the dealer will run afoul of Federal and state Lemon Laws that give you very specific rights, and recourse (contact an Attorney; we are Mechanics, NOT attorneys). Consequently, if the vehicle is still under warranty, to save yourself money do be sure to seek a resolution from the dealer. If the vehicle is not under warranty, obviously a certified Mechanic from YourMechanic could identify the electrical fault and resolve this for you. If you want to go that route, please simply request a no start diagnostic -electrical system 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.

When the car heats up the brakes squeak. When the car cools down they’re fine, but when it heats up they start squeaking again.
ANSWER : Hi, thanks for writing in. Pads and rotors can become "glazed" if overheated. If this happens, the bonding material in the brake pads can rise up out of the pads and transfer to the rotors, causing a bluish discoloration to the rotors and cause a squeak. Removing the pads, sanding the surface of them and the rotors may help. If not, a light resurfacing of the rotors and using some brake lube on the backs of the pads should help. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect your brake system for you, and make or suggest any repairs or cleaning as needed.

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

My car is over heating. It doesn’t take long for it to over heat till it is smoking and I have to turn the car off.
ANSWER : There are a couple of possibilities for such a rapid overheating situation. The thermostat may have failed in the "closed" position preventing the hot water from circulating and cooling in the radiator. The water pump or the serpentine drive belt may have failed and the hot water does not get circulated through the radiator.

If one of the head gaskets on the engine has failed, combustion gasses from one or more cylinders can "superheat" engine coolant very quickly. If the coolant level is low and there are air pockets in the engine, the coolant is literally "boiled away" inside the engine, creating far higher temperatures than an engine that is "full of coolant".

It is recommended that you get a mobile, professional mechanic, such as one from YourMechanic, to perform an inspection and determine the cause of the overheating.

My car is Renault megane 2003 model manual, my problem is the car stooped it self in the road light & it cant start now.
ANSWER : Hello and thanks for contacting YourMechanic. There are 3 things that could cause the symptoms that you are currently experiencing. One is the ignition coils getting too hot and failing.

The second is the trigger to the ignition coils could be cutting out. The camshaft and crankshaft sensors are what control the trigger to the ignition coils. If one of the sensors are not responding correctly, then the trigger may get dropped by the computer. The computer would shut down the engine to prevent any problems.

The third problem that could effect this issue is a faulty neutral safety switch on the clutch. Check the harness and wires to the switch on the clutch and see if they are clean and free from corrosion. Make sure that the switch is not binding up or sticking. I recommend replacing the neutral safety switch, then retesting. If the system continues, then replace the crankshaft and camshaft sensors. If the symptoms are still present, then the computer is locking the trigger out and shutting off the engine. Then you would need to flash or replace the computer. If you would like to have an expert scope this out in person, a qualified professional from YourMechanic can diagnose the stalling issue and let you know exactly what needs repair.

My car will be starting perfect and when the gas tank gets lower it will start having problems .
ANSWER : Based on the information you gave, it sounds like a possible fuel starvation issue, caused by a partially blocked, in-tank fuel filter or a crack in the fuel pump housing. The remedy would be to replace the fuel pump assembly and filter. The overheating may be caused by several things, including a stuck thermostat, faulty water pump, or even a cracked head gasket. I suggest having a certified technician, like one from YourMechanic, inspect the relevant systems to pinpoint the cause of your vehicle’s hard starting issue and overheating problem.

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.