Why would my dura star mini split system work in every mode except heat

NOTIFY COMFORT AIRE WE ARE NO PART OF THAT COMPANY

It takes a while to cool the refrigerant down first.

its either out of refrigerant or in heat pump mode

Look, if you select a temperature above ambient temperature, it will switch from cooling to heating.(assuming that the aircon has a heat pump. most do these days.) Just dont rush the aircon because every time you make a setting change, it takes a while to regulate.

This unit comes with a remote control (optional wall mounted wired thermostat available) as a standard feature. This unit is precharged with the environment friendly R-410a refrigerant. No additional refrigerant is needed if the line set is 49 feet in lenght or shorter. In addition to its very high 20 SEER efficiency rating, the 15RLQ is only 31 in. long which makes it the smallest Mini-Split System in its category through out the industry.
This category of equipment is ideal for smaller spaces where spot cooling is required. Several models in this category are ENERGY STAR Certified, meaning they save you money on your utility bill. Residential applications including sunrooms and additions are made easier with these air conditioners and heat pumps. Do you have a warm spot in your home? Fujitsu mini-splits can provide extra cooling capacity for those hard to cool areas. Commercially, their small size makes them ideal for small offices, providing individual temperature control.
Fujitsu's I.A.Q. Systems provide residential and commercial property owners an innovative solution for clean, temperature-controlled indoor air. The Halcyon IAQ systems deliver powerful heating and cooling, are designed for ease of use and maintenance, and feature an unobtrusive design which can be integrated easily into any decor. The Halcyon IAQ systems filter dust, pollen and odor making them the perfect addition to any home!
Standard Features

• Wireless Remote Control
• Plasma Filter
• Sleep Timer
• 24 Hour Timer
• Dry Mode
• Auto Louver: Up/Down
• Auto Mode
• Quiet Mode
• Auto Restart/Rest
• Auto Changeover
• Low Ambient
• Cold Prevention

Warranty All Fujitsu ductless mini-split air conditioners and heat pumps come with a 2 year parts and 6 year compressor warranty.
Important: All installations must be performed or supervised by a certified HVAC technician in order for the warranty to be valid.

Turn thermostat switch to 'cool' setting. It's a 'heat pump' and is in the heat mode.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

that's normal

My Mistral was working yesterday (on heat) now it won't. Just sits there as if warming up but actually blows out freezing air - on "sun" mode.

Check that you are on the correct mode setting. Open the remote and press the mode button (the one with about four little icons, star, teardrop, triangle and sun) until you get to the mode you require. If cooling required, select the star or crystal, if heating required select the sun (circle with little lines)

Heat pumps have saftey circuits that prevent liquid flooding of the compressor. Inadequate airflow across the evaporator in cooling can trip this circuit. Have your package unit serviced with particular attention to cleaning the evaporator coil and be sure your filters are clean and changed frequently in the summer months. Hope this helps GL!