Heat pump making a hissing noisePost created: 2012-11-08 Type of Equipment: Heat Pump Views: 250
This question was created on the page: https://www.furnacecompare.com/heat-pumps/index.html.
On 2012-11-09 JB wrote:
Hard to say what this could be without more information. The first question would be is it a new system or new to you (e.g. you just moved into the house)? I would also ask if this is happening as the heat pump is transitioning from cooling to heating or vice-versa?
If so it may be a common noise associated with the heat pump going into a defrost cycle.
The noise could also indicate that a valve inside the compressor (internal relief valve?) is faulty and needs to be replaced. If this is the case then you will need an HVAC pro to come and do a diagnostic to determine the problem and replace the valve if that is what's required.
Best of luck!