diff --git a/multiace/i18n/de.json b/multiace/i18n/de.json
index 6f2b5fcb..8d38a54e 100644
--- a/multiace/i18n/de.json
+++ b/multiace/i18n/de.json
@@ -54,7 +54,7 @@
       "mode_1": "Kammer kühlen",
       "mode_2": "Kammer vorheizen",
       "mode_3": "Heiße Kammer",
-      "enc_locked_print": "Nicht während eines Drucks: der Gehäusemodus kommt aus der Slicer-Datei.",
+      "enc_hint_print": "Ein laufender Modus kann den Abluftwert während des Drucks wieder überschreiben.",
       "enc_locked_mode": "Das Gehäuse läuft in einem Modus und steuert seine Lüfter selbst. Zuerst Lüfter aus.",
       "restart_blocked": "Gesperrt, solange ein Druck läuft",
       "light": "Licht",
diff --git a/multiace/i18n/en.json b/multiace/i18n/en.json
index 69477920..22c89675 100644
--- a/multiace/i18n/en.json
+++ b/multiace/i18n/en.json
@@ -54,7 +54,7 @@
       "mode_1": "Cooling chamber",
       "mode_2": "Preheating chamber",
       "mode_3": "Hot chamber",
-      "enc_locked_print": "Not during a print: the enclosure mode comes from the sliced file.",
+      "enc_hint_print": "A running mode may override the exhaust value while the print runs.",
       "enc_locked_mode": "The enclosure is running a mode and drives its fans itself. Use Fans off first.",
       "restart_blocked": "Blocked while a print is running",
       "light": "Light",
diff --git a/multiace/i18n/zh.json b/multiace/i18n/zh.json
index 568ee73f..6a95b795 100644
--- a/multiace/i18n/zh.json
+++ b/multiace/i18n/zh.json
@@ -54,7 +54,7 @@
       "mode_1": "腔体降温",
       "mode_2": "腔体预热",
       "mode_3": "高温腔体",
-      "enc_locked_print": "打印期间不可用：机箱模式由切片文件决定。",
+      "enc_hint_print": "模式运行期间，打印过程中排气风扇的数值可能会被其覆盖。",
       "enc_locked_mode": "机箱正在运行某个模式并自行控制风扇。请先点击“关闭风扇”。",
       "restart_blocked": "打印进行中，已禁用",
       "light": "灯光",
diff --git a/multiace/web/backend/main.py b/multiace/web/backend/main.py
index fdf1b684..84409c66 100644
--- a/multiace/web/backend/main.py
+++ b/multiace/web/backend/main.py
@@ -2652,12 +2652,13 @@ async def _require_object(name: str, what: str) -> dict:
         raise HTTPException(409, f"this printer has no {what}")
     return status
 
-async def _require_enclosure_idle() -> None:
+async def _require_enclosure_drivable() -> None:
     """409 unless the enclosure fans may be driven directly: an enclosure is
-    attached, no print is running, and stock is not running a mode. In modes
-    1 to 3 stock drives the fans itself (dynamically in cool mode), so a
-    direct speed would compete with it, and during a print the mode usually
-    comes from the sliced file."""
+    attached and, outside a print, stock is not running a mode. During a
+    print the fans are allowed whatever the mode (stock itself accepts
+    SET_PURIFIER at any time); a running mode may override the exhaust value
+    again, which the UI says. Outside a print, modes 1 to 3 drive the fans
+    themselves (dynamically in cool mode), so a direct speed would compete."""
     try:
         status = await _print_status()
     except httpx.HTTPError as e:
@@ -2668,8 +2669,7 @@ async def _require_enclosure_idle() -> None:
     if not purifier.get("power_detected"):
         raise HTTPException(409, "no enclosure is attached")
     if (status.get("print_stats") or {}).get("state") in ("printing", "paused"):
-        raise HTTPException(409, "not during a print: the enclosure mode comes "
-                                 "from the sliced file")
+        return
     if purifier.get("mode") != 0:
         raise HTTPException(409, "the enclosure is running a mode and drives "
                                  "its fans itself; stop it first")
@@ -2712,7 +2712,7 @@ async def print_control(request: Request, req: PrintControl) -> dict:
             # One enclosure fan directly (stock SET_PURIFIER). SPEED=0 starts
             # stock's delayed turn-off rather than stopping at once.
             if not mocked:
-                await _require_enclosure_idle()
+                await _require_enclosure_drivable()
             script = f"SET_PURIFIER FAN={verb} SPEED={applied / 100:.2f}"
         else:
             if not mocked:
diff --git a/multiace/web/frontend/app.js b/multiace/web/frontend/app.js
index 361dcbe9..6f71c110 100644
--- a/multiace/web/frontend/app.js
+++ b/multiace/web/frontend/app.js
@@ -7497,9 +7497,10 @@ createApp({
       resume: printCtl.state === "paused",
       cancel: printCtl.state === "printing" || printCtl.state === "paused",
     }));
-    // The enclosure fans may be driven directly only when stock is not: not
-    // during a print (the mode comes from the sliced file) and not while a
-    // mode runs. The server enforces both; this only explains it.
+    // Outside a print the fans may be driven directly only while no mode
+    // runs; the server enforces it, this only explains it. During a print
+    // they are always allowed (stock accepts it too); a running mode may
+    // override the exhaust value, which is only a hint.
     // Stock's defect detection watches the print with the camera, which needs
     // the chamber light: while it is on during a print the light stays on.
     // The server refuses it too; this only disables the switch and explains.
@@ -7508,12 +7509,15 @@ createApp({
       && (printCtl.state === "printing" || printCtl.state === "paused"));
     const enclosureLock = computed(() => {
       const e = printCtl.enclosure;
-      if (printCtl.state === "printing" || printCtl.state === "paused") {
-        return t("ui.control.enc_locked_print");
-      }
+      if (printCtl.state === "printing" || printCtl.state === "paused") return "";
       if (e && e.mode) return t("ui.control.enc_locked_mode");
       return "";
     });
+    const enclosureHint = computed(() => {
+      const e = printCtl.enclosure;
+      return (printCtl.state === "printing" || printCtl.state === "paused")
+        && e && e.mode ? t("ui.control.enc_hint_print") : "";
+    });
     const enclosureModeText = computed(() => {
       const e = printCtl.enclosure;
       if (!e || e.mode === null || e.mode === undefined) return "";
@@ -7609,6 +7613,16 @@ createApp({
     function printCtlReset(verb) {
       printCtlRelease(verb, verb === "fan" ? 0 : 100);
     }
+    // The target boxes show the current target, so a spinner arrow steps from
+    // the real value instead of from an empty box. While the user is in a
+    // box the typed value wins over the readback; leaving the box (blur)
+    // goes back to showing the target.
+    const printCtlTempDraft = reactive({nozzle: null, bed: null});
+    function printCtlTempShown(verb) {
+      if (printCtlTempDraft[verb] !== null) return printCtlTempDraft[verb];
+      const target = printCtl[verb].target;
+      return target === null ? "" : Math.round(target);
+    }
     // An empty box is "nothing typed", not 0: sending 0 would switch the
     // heater off.
     function printCtlHeat(verb, ev) {
@@ -7616,7 +7630,6 @@ createApp({
       if (raw === "") return;
       const v = Number(raw);
       if (Number.isFinite(v)) sendPrintControl(verb, v);
-      ev.target.value = "";
     }
     // Restart Firmware / Restart Printer. Refused by the server while a
     // print runs and under a managed install; the buttons mirror that. After
@@ -7887,7 +7900,8 @@ createApp({
       webcam, webcamSrc, webcamVideo, reloadWebcam,
       printCtl, printCtlLimits, printCtlDraft, printCtlBusy, printCtlError, printCtlCan,
       printCtlNotice, printCtlQueued, printCtlRestart, printCtlRestartBlocked,
-      enclosureLock, enclosureModeText, lightLocked,
+      printCtlTempDraft, printCtlTempShown,
+      enclosureLock, enclosureHint, enclosureModeText, lightLocked,
       printCtlSlide, printCtlRelease, printCtlReset, printCtlHeat, printCtlCancel,
       sendPrintControl,
       consoleLines, consoleFollow, consoleEl, loadConsole, consoleTime,
diff --git a/multiace/web/frontend/index.html b/multiace/web/frontend/index.html
index b7b76a61..6caa36ae 100644
--- a/multiace/web/frontend/index.html
+++ b/multiace/web/frontend/index.html
@@ -1429,6 +1429,9 @@ <h3>{{ t('ui.control.print') }}</h3>
             <input type="number" class="pc-temp-in"
                    min="0" :max="printCtlLimits.nozzle.max"
                    :placeholder="t('ui.control.target')"
+                   :value="printCtlTempShown('nozzle')"
+                   @input="printCtlTempDraft.nozzle = $event.target.value"
+                   @blur="printCtlTempDraft.nozzle = null"
                    @change="printCtlHeat('nozzle', $event)">
           </div>
           <div class="pc-row pc-temps">
@@ -1438,6 +1441,9 @@ <h3>{{ t('ui.control.print') }}</h3>
             <input type="number" class="pc-temp-in"
                    min="0" :max="printCtlLimits.bed.max"
                    :placeholder="t('ui.control.target')"
+                   :value="printCtlTempShown('bed')"
+                   @input="printCtlTempDraft.bed = $event.target.value"
+                   @blur="printCtlTempDraft.bed = null"
                    @change="printCtlHeat('bed', $event)">
           </div>
 
@@ -1463,9 +1469,10 @@ <h3>{{ t('ui.control.print') }}</h3>
           <p v-if="lightLocked" class="muted small">{{ t('ui.control.light_locked') }}</p>
 
           <!-- Only with an enclosure attached (the printer's own attach detection).
-               Fans can be set directly only when stock is not driving them: the
-               server refuses it during a print and while a mode runs, and the
-               sliders say why. "Fans off" returns to idle and stops both at once. -->
+               Outside a print the fans can be set directly only while no mode
+               runs (the sliders say why). During a print they always can; a
+               running mode may override the exhaust value, which the hint
+               says. "Fans off" returns to idle and stops both at once. -->
           <div class="pc-enc" v-if="printCtl.enclosure && printCtl.enclosure.attached">
             <div class="pc-row pc-enclosure">
               <span>{{ t('ui.control.enclosure_fans') }}</span>
@@ -1483,6 +1490,7 @@ <h3>{{ t('ui.control.print') }}</h3>
               <b>{{ Math.round(printCtl.enclosure[f]) }} %</b>
             </label>
             <p v-if="enclosureLock" class="muted small">{{ enclosureLock }}</p>
+            <p v-else-if="enclosureHint" class="muted small">{{ enclosureHint }}</p>
           </div>
 
           <!-- Z offset is BUTTONS, never a slider: a slider makes it easy to
diff --git a/tests/unit/test_print_control.py b/tests/unit/test_print_control.py
index 5fc6034f..7f7473fe 100644
--- a/tests/unit/test_print_control.py
+++ b/tests/unit/test_print_control.py
@@ -416,7 +416,8 @@ def test_there_is_no_way_to_pick_a_mode_or_name_a_fan(self, client, printer):
 
 
 class TestEnclosureFans:
-    """Direct fan speed: only with an enclosure attached, idle, and no print."""
+    """Direct fan speed: only with an enclosure attached; outside a print also
+    only while no mode runs."""
     IDLE = {"purifier": PURIFIER_OBJ, "print_stats": {"state": "standby"}}
 
     @pytest.mark.parametrize("fan,value,script,applied", [
@@ -440,8 +441,6 @@ def test_a_value_is_required(self, client, printer):
         ({"print_stats": {"state": "standby"}}, "no enclosure"),
         ({"purifier": {**PURIFIER_OBJ, "power_detected": False},
           "print_stats": {"state": "standby"}}, "not attached"),
-        ({"purifier": PURIFIER_OBJ, "print_stats": {"state": "printing"}}, "printing"),
-        ({"purifier": PURIFIER_OBJ, "print_stats": {"state": "paused"}}, "paused"),
         ({"purifier": {**PURIFIER_OBJ, "mode": 1}, "print_stats": {"state": "standby"}}, "cool"),
         ({"purifier": {**PURIFIER_OBJ, "mode": 2}, "print_stats": {"state": "standby"}}, "preheat"),
         ({"purifier": {**PURIFIER_OBJ, "mode": 3}, "print_stats": {"state": "standby"}}, "hot"),
@@ -454,6 +453,21 @@ def test_refused_and_nothing_sent(self, client, printer, status, why, fan):
         assert post(client, fan, 50).status_code == 409, why
         assert printer.sent == []
 
+    @pytest.mark.parametrize("state", ["printing", "paused"])
+    @pytest.mark.parametrize("mode", [0, 1, 3])
+    @pytest.mark.parametrize("fan", ["exhaust", "inner"])
+    def test_allowed_during_a_print_whatever_the_mode(
+            self, client, printer, state, mode, fan):
+        printer.status = {"purifier": {**PURIFIER_OBJ, "mode": mode},
+                          "print_stats": {"state": state}}
+        assert post(client, fan, 50).status_code == 200
+        assert printer.sent == [f"SET_PURIFIER FAN={fan} SPEED=0.50"]
+
+    def test_a_missing_enclosure_is_still_refused_during_a_print(self, client, printer):
+        printer.status = {"print_stats": {"state": "printing"}}
+        assert post(client, "exhaust", 50).status_code == 409
+        assert printer.sent == []
+
     def test_an_unreachable_moonraker_blocks_it(self, main, client, printer, monkeypatch):
         async def boom(path):
             raise httpx.ConnectError("down")