Recent reports of hard-sell cold calls to Auckland and Tauranga residents saying your heat pump must be annually cleaned and re-gassed has Andy Goodall of Comfort Air Conditioning Ltd concerned.

Andy says he worries cold callers are playing on popular misconceptions that the units will run out of refrigerant or your warranty will be voided.

While it's true air conditioners should be kept in a clean and clear state to run more effectively and last longer, a properly installed heat pump should never need re-gassing.

Andy recommends you don't get pushed into an expensive decision without getting a price comparison. He says a standard service, clean and sanitise should take about 45 minutes and cost about $100.

Alternatively, you can do the main items that need regular attention yourself.

'Clean the filters, which are under the front cover of the inside unit,” says Andy.

'I suggest soaking the filters in warm soapy water, then rinsing with a garden hose. This will do a better clean than scrubbing or vacuuming, which can damage the filter mesh.”

Keep the outdoor unit free of debris. Sweep or wash the area around the outdoor unit and coil. Andy also recommends a regular spray of surface insecticide to keep the bugs away.

Should you suspect the unit may not be working well or it requires a more thorough clean than you can manage yourself, Andy says a safer option is to use a specialist company that services heat pumps as removing the covers exposes you to risks from the high-pressure gases and electrics within.