Sticking high side coupler

[tab a]

I have a problem with the high side quick connect fitting on my 97 Ranger. It is oriented straight up, and the valve is sticking: When connected to my gauges it might show no pressure, some pressure or full pressure. Pushing the gauge coupler down, releasing, repeating, will get it to open completely and show accurate pressures. This MAY be due to using some Big Blue bubble solution (it's quite sticky), looking for a leak. This fitting does NOT have a Shrader valve that can be unscrewed.

The system is empty at the moment. Any solvent you think I could try without problems with it getting in the system?

Thanks.

[Cusser]

On my 1994 Suburban I had to press down on the high side coupler to get an R134a pressure reading. I blamed that on bad design by GM, the coupler worked fine on other vehicles.