How to troubleshoot a furnace that won’t work.

There are a few things that will cause any furnace to either stop running, or only deliver cold air, so here are a few easy DIY furnace repair tipsthat may get you warmed up without having to call an HVAC professional. It is at least a place to start, so you aren’t paying someone to come tell you that your thermostat is set too low.

What to do if a furnace only blows cold air

妨碍炉子正常运行的最常见的问题，也是要检查的第一件事，就是恒温器设置是否正确。Make sure the temperature is high enough to activate it, and that the thermostat is set to ‘heat’ and the fan set to ‘auto’. If that doesn’t fix the problem then the next likely cause would be the filter.

Dust and dirt restricts airflow, so if the furnace filter is cloggedit will slow the movement of air enough that whatever hot air ‘might’ have gotten to its destination at a normal air pressure has simply cooled by the time it arrived. Also, preventing that air flow can cause the heat exchanger in the furnace to overheat and shut off too quickly. Try those two solutions and let us know if you notice any difference.

What to do if a furnace blower won’t stop running

当炉子上的鼓风机不关闭时，首先要检查的是恒温器设置为on，而不是AUTO。If that isn’t the issue, the next most likely cause is a faulty relay. That’s not something the average homeowner would be able to fix, you would need to contact an HVAC professional.

What to do when a furnace is noisy and rattling

If a furnace seems to be working fine but is making more noise than it used to, first check that the access panel is properly fastened. Over time screws can work themselves loose just from the vibrations of normal operation, or perhaps they weren’t tightened properly the last time it was removed and replaced. See if any screws on the access panel seem to be loose and tighten them, this may be the source of the problem.

If it's not the access panel, then the noise may be originating from the blower fan. The fan is held in place by one or two set screws. These can also work themselves loose over time, and if the fan is not secured properly it will definitely rattle around. The same quick fix is possible, so check the screws and tighten them if needed and see if that makes a difference.

For another quick DIY furnace noise fix if those don’t work, check to see if there is any debris stuck inside the fan that may be impeding its movement. That about covers the easy DIY furnace fixes, the next most likely cause would be bearings in the fan wearing out.

Over time, worn bearings will cause something like a grinding sound of metal on metal, or maybe sound like a diesel engine idling. It may be intermittent at first, but as time goes on it can be more frequent, and increasingly unbearable to listen to. Whether it is you as a homeowner or a professional that does the work, there is not much besides replacing the motor that will fix that problem.

Furnace is squeaking from a belt

Some furnaces have a belt drive motor than can wear down overtime, and may start to squeak just like the alternator belt in a car. If the belt is out of alignment or if it’s slipping, it may be something you can fix yourself by adjusting or tightening it. If tightening it in place doesn’t solve the issue then you may need to adjust its position, that is as good a time as any to remove it and clean it first. Only do this if it is within your general wheelhouse of knowledge and that you have the right tools, and be sure to make sure the furnace is shut off.

What to do if a furnace won’t run at all

If your furnace will not blow any air at all, first you need to find out why it is not turning on, and it could be any of the following easy fixes. Like above, the first thing to check is the thermostat; make sure it simply isn’t programmed to be ‘off’.Be sure it is set to ‘heat’ and the fan is set to ‘auto’.

如果这还不能激活它，下一步看看你的电气面板，看看保险丝或断路器是否烧断了。如果你的电器面板上有保险丝，你可以在面板上找到一个相同的保险丝，把它换掉一会儿作为故障排除措施。如果它开始跑了，你就知道你需要一个新的保险丝。

If your electrical panel is on a breaker system, first check that it isn’t tripped, but flick it off and back on anyways as that may reset it. Next, locate the furnace power switch that is likely on the side of the furnace and make sure that it’s on in case it has been accidentally bumped to the off position.

有些设备有一个切断开关，当鼓风机门没有完全密封的时候，可以阻止炉子运行，所以你可以打开那个开关，如果有的话，定位那个开关，确保它可以自由移动，当你把门重新打开的时候，它是被激活的。

Troubleshoot a high efficiency condenser furnace that won’t work

在高效率的凝汽炉中，产生的副产品是水，它会有一个泵来除去这些水。There is probably an overflow safety switch wired to the furnace that will shut the furnace off if the pump fails. There should be a small reservoir you can pour some water into to check that the pump is working.

Check safety switches on modern furnaces

Newer and modern furnaces will have safety switches that set the furnace into a lockout mode that will shut down the furnace when it is not safe to operate.These include the flame sensor, pressure switch, flame rollout switch and limit switch. If the switch is tripped it will try to cycle on a few times, but if it can’t successfully start it will go in a hard lockdown, possibly for an hour or longer.

在这里，你需要你的炉手册来发现哪个系统运行不正常。我们没有简单的解决方法，因为这是你可能需要联系专业人士的地方。你总是有机会通过电话得到一个小的修复，手边有你的手册和一些故障诊断信息提供给服务人员会很有帮助，可能意味着快速修复和等待服务呼叫之间的区别。

最后一件重要的事情-如果排除或修理一个有故障的炉子，并且炉子是用天然气或丙烷运行的，要非常小心，不要试图修理任何天然气部件，如阀门或指示灯区域。让专业人士来做吧。

And if you smell rotten eggs or hear the hissing sound of escaping gas, it could be a natural gas leak which might be very dangerous, so:

1. Stop what you’re doing.不要使用手机或座机，不要吸烟、点燃火柴、操作电器开关或制造任何其他点火源。
2. Get outside immediately.当你离开的时候，把身后的门和已经打开的窗户都打开。
3. Report it.Once outside, CALL 911 or your local emergency number, and your gas service provider’s 24-hour emergency line.
4. Turn off the gas tap at the meter outsideif you are confident you know what and where it is.
5. Stay outside,tell the official if you turned off the gas tap, and stay outside until an official says it’s safe to go back in.

Now you know abouthow to trouble shoot a furnace that won't heat; learn more aboutefficient home heating systems in eco homesin theseguide pagesaboutsustainable and resilient green building: Why natural gas is being phased out of new homes, and when Buying guide for furnance filters and for HRVS and ERVs - why MERV and HEPA filters are important Maintaining healthy indoor air quality in homes How to service HRV & ERV units at home for optimum efficiency Find more about green home constructionin the EcohomeGreen Building Guide pages- also, learn more aboutthe benefits of a free Ecohome Network Membership here.