Parts for your 1999 Toyota Hiace-Heater tap

1999 Toyota Hiace heater tap — what it does and how to look after it

Based on technical references, the 1999 Toyota Hiace is fitted with a heater tap (also called a heater control valve). Toyota’s Electronic Parts Catalog for the H100 series (1995–2004) lists a “Water Valve Assy, Heater” across RZH/LH/KZH variants, and the factory Hiace Repair Manual for the heating/air-conditioning section includes inspection and adjustment of the heater water valve. Australian and New Zealand aftermarket catalogues (Dayco, Gates, Repco) also specify a direct-fit heater tap for 1990s Hiace models, confirming it’s a normal part of the system.

On a ’99 Hiace, the heater tap sits inline on the heater hoses and is cable-operated from the cabin temperature slider. Its job is to regulate hot coolant flow into the heater core. Open the tap and you get cosy warm air, close it and it stops heat soak into the cabin and helps the A/C stay crisp on hot days. It also lets techs isolate the heater circuit during cooling-system work, handy on a cab-over van with long hose runs.

As part of regular servicing, it’s smart to check the tap every time the coolant is inspected. Look for seepage around the spindle, perished hose connections, stiffness in the lever, or a temperature slider that feels notchy. If the cabin temp won’t change, you’re stuck on full hot, or the A/C never feels cold at idle, a sticky or failed tap is a usual suspect.

Replacement is straightforward: drain or clamp to keep coolant below the tap, mark hose orientation, swap the valve, fit new clamps, then refill and bleed the system with the heater control set to HOT. Because Hiace has a long cooling circuit, use a spill-free funnel and take time to burp air—an airlock can cause overheating or weak cabin heat. If your van has a rear heater, there may be an extra valve to check as well.

• Inspect operation seasonally by sliding the temp lever and feeling hose temperature change.
• Renew old hoses and clamps when replacing the tap to prevent weeps.
• Always use the correct Toyota-approved coolant mix and bleed thoroughly.

Popular questions

Where is the heater tap on a 1999 Hiace?
It’s mounted inline on the heater hoses that feed the front heater core, typically near the heater box/bulkhead area. On most AUS/NZ right-hand-drive vans, you’ll find it close to where the heater pipes pass through the body and the control cable can reach it from the dash slider.

What are the symptoms of a failing heater tap?
Common giveaways are no heat or constant heat regardless of the slider position, coolant drips around the valve, and a stiff or loose-feeling temperature control. You might also notice weak A/C because hot coolant is bleeding through the core even when you want it shut.

Do all 1999 Hiace models have a heater tap?
Most Australian and New Zealand–delivered 1999 Hiace variants do. Vans with a rear heater may use an additional valve for the rear circuit. Very occasionally, vehicles that have been modified or repaired in the past might have the tap bypassed—worth a look if the system behaves oddly.